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haproxy/doc/lua-api/index.rst
Aurelien DARRAGON 84f7525c5b DOC: lua: fix filters.txt file location 
At the beginning of the filter class section, we encourage the user to
check out filters.txt file to get to know how the filters API works
within haproxy.

However the file location is incorrect. The proper directory to look for
the file is: doc/internals/api.

It should be backported up to 2.5.
2024-05-10 11:02:56 +02:00

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.. toctree::
:maxdepth: 2
How Lua runs in HAProxy
=======================
HAProxy Lua running contexts
----------------------------
The Lua code executed in HAProxy can be processed in 2 main modes. The first one
is the **initialisation mode**, and the second is the **runtime mode**.
* In the **initialisation mode**, we can perform DNS solves, but we cannot
perform socket I/O. In this initialisation mode, HAProxy still blocked during
the execution of the Lua program.
* In the **runtime mode**, we cannot perform DNS solves, but we can use sockets.
The execution of the Lua code is multiplexed with the requests processing, so
the Lua code seems to be run in blocking, but it is not the case.
The Lua code is loaded in one or more files. These files contains main code and
functions. Lua has 8 execution contexts.
1. The Lua file **body context**. It is executed during the load of the Lua file
in the HAProxy `[global]` section with the directive `lua-load`. It is
executed in initialisation mode. This section is use for configuring Lua
bindings in HAProxy.
2. The Lua **init context**. It is a Lua function executed just after the
HAProxy configuration parsing. The execution is in initialisation mode. In
this context the HAProxy environment are already initialized. It is useful to
check configuration, or initializing socket connections or tasks. These
functions are declared in the body context with the Lua function
`core.register_init()`. The prototype of the function is a simple function
without return value and without parameters, like this: `function fcn()`.
3. The Lua **task context**. It is a Lua function executed after the start
of the HAProxy scheduler, and just after the declaration of the task with the
Lua function `core.register_task()`. This context can be concurrent with the
traffic processing. It is executed in runtime mode. The prototype of the
function is a simple function without return value and without parameters,
like this: `function fcn()`.
4. The **action context**. It is a Lua function conditionally executed. These
actions are registered by the Lua directives "`core.register_action()`". The
prototype of the Lua called function is a function with doesn't returns
anything and that take an object of class TXN as entry. `function fcn(txn)`.
5. The **sample-fetch context**. This function takes a TXN object as entry
argument and returns a string. These types of function cannot execute any
blocking function. They are useful to aggregate some of original HAProxy
sample-fetches and return the result. The prototype of the function is
`function string fcn(txn)`. These functions can be registered with the Lua
function `core.register_fetches()`. Each declared sample-fetch is prefixed by
the string "lua.".
.. note::
It is possible that this function cannot found the required data in the
original HAProxy sample-fetches, in this case, it cannot return the
result. This case is not yet supported
6. The **converter context**. It is a Lua function that takes a string as input
and returns another string as output. These types of function are stateless,
it cannot access to any context. They don't execute any blocking function.
The call prototype is `function string fcn(string)`. This function can be
registered with the Lua function `core.register_converters()`. Each declared
converter is prefixed by the string "lua.".
7. The **filter context**: It is a Lua object based on a class defining filter
callback functions. Lua filters are registered using
`core.register_filter()`. Each declared filter is prefixed by the string
"lua.".
8. The **event context**: Inside a function that handles events subscribed
through `core.event_sub()` or `Server.event_sub()`.
HAProxy Lua Hello world
-----------------------
HAProxy configuration file (`hello_world.conf`):
::
global
lua-load hello_world.lua
listen proxy
bind 127.0.0.1:10001
tcp-request inspect-delay 1s
tcp-request content use-service lua.hello_world
HAProxy Lua file (`hello_world.lua`):
.. code-block:: lua
core.register_service("hello_world", "tcp", function(applet)
applet:send("hello world\n")
end)
How to start HAProxy for testing this configuration:
::
./haproxy -f hello_world.conf
On other terminal, you can test with telnet:
::
#:~ telnet 127.0.0.1 10001
hello world
Usage of load parameters
------------------------
HAProxy lua-load(-per-thread) directives allow a list of parameters after
the lua file name. These parameters are accessible through an array of args
using this code `local args = table.pack(...)` in the body of loaded file.
Below, a new version of the hello world using load parameters
HAProxy configuration file (`hello_world.conf`):
::
global
lua-load hello_world.lua "this is not an hello world"
listen proxy
bind 127.0.0.1:10001
tcp-request inspect-delay 1s
tcp-request content use-service lua.hello_world
HAProxy Lua file (`hello_world.lua`):
.. code-block:: lua
local args = table.pack(...)
core.register_service("hello_world", "tcp", function(applet)
applet:send(args[1] .. "\n")
end)
Core class
==========
.. js:class:: core
The "core" class contains all the HAProxy core functions. These function are
useful for the controlling of the execution flow, registering hooks,
manipulating global maps or ACL, ...
"core" class is basically provided with HAProxy. No `require` line is
required to uses these function.
The "core" class is static, it is not possible to create a new object of this
type.
.. js:attribute:: core.silent
:returns: integer
This attribute is an integer, it contains the value -1. It is a special value
used to disable logging.
.. js:attribute:: core.emerg
:returns: integer
This attribute is an integer, it contains the value of the loglevel
"emergency" (0).
.. js:attribute:: core.alert
:returns: integer
This attribute is an integer, it contains the value of the loglevel
"alert" (1).
.. js:attribute:: core.crit
:returns: integer
This attribute is an integer, it contains the value of the loglevel
"critical" (2).
.. js:attribute:: core.err
:returns: integer
This attribute is an integer, it contains the value of the loglevel
"error" (3).
.. js:attribute:: core.warning
:returns: integer
This attribute is an integer, it contains the value of the loglevel
"warning" (4).
.. js:attribute:: core.notice
:returns: integer
This attribute is an integer, it contains the value of the loglevel
"notice" (5).
.. js:attribute:: core.info
:returns: integer
This attribute is an integer, it contains the value of the loglevel
"info" (6).
.. js:attribute:: core.debug
:returns: integer
This attribute is an integer, it contains the value of the loglevel
"debug" (7).
.. js:attribute:: core.proxies
**context**: init, task, action, sample-fetch, converter
This attribute is a table of declared proxies (frontend and backends). Each
proxy give an access to his list of listeners and servers. The table is
indexed by proxy name, and each entry is of type :ref:`proxy_class`.
.. Warning::
if you declared a frontend and backend with the same name, only one of
them will be listed.
:see: :js:attr:`core.backends`
:see: :js:attr:`core.frontends`
.. js:attribute:: core.backends
**context**: init, task, action, sample-fetch, converter
This attribute is a table of declared proxies with backend capability. Each
proxy give an access to his list of listeners and servers. The table is
indexed by the backend name, and each entry is of type :ref:`proxy_class`.
:see: :js:attr:`core.proxies`
:see: :js:attr:`core.frontends`
.. js:attribute:: core.frontends
**context**: init, task, action, sample-fetch, converter
This attribute is a table of declared proxies with frontend capability. Each
proxy give an access to his list of listeners and servers. The table is
indexed by the frontend name, and each entry is of type :ref:`proxy_class`.
:see: :js:attr:`core.proxies`
:see: :js:attr:`core.backends`
.. js:attribute:: core.thread
**context**: task, action, sample-fetch, converter, applet
This variable contains the executing thread number starting at 1. 0 is a
special case for the common lua context. So, if thread is 0, Lua scope is
shared by all threads, otherwise the scope is dedicated to a single thread.
A program which needs to execute some parts exactly once regardless of the
number of threads can check that core.thread is 0 or 1.
.. js:function:: core.log(loglevel, msg)
**context**: body, init, task, action, sample-fetch, converter
This function sends a log. The log is sent, according with the HAProxy
configuration file, to the loggers relevant to the current context and/or
to stderr if it is allowed.
The exact behaviour depends on tune.lua.log.loggers and tune.lua.log.stderr.
:param integer loglevel: Is the log level associated with the message. It is a
number between 0 and 7.
:param string msg: The log content.
:see: :js:attr:`core.emerg`, :js:attr:`core.alert`, :js:attr:`core.crit`,
:js:attr:`core.err`, :js:attr:`core.warning`, :js:attr:`core.notice`,
:js:attr:`core.info`, :js:attr:`core.debug` (log level definitions)
:see: :js:func:`core.Debug`
:see: :js:func:`core.Info`
:see: :js:func:`core.Warning`
:see: :js:func:`core.Alert`
.. js:function:: core.Debug(msg)
**context**: body, init, task, action, sample-fetch, converter
:param string msg: The log content.
:see: :js:func:`core.log`
Does the same job than:
.. code-block:: lua
function Debug(msg)
core.log(core.debug, msg)
end
..
.. js:function:: core.Info(msg)
**context**: body, init, task, action, sample-fetch, converter
:param string msg: The log content.
:see: :js:func:`core.log`
.. code-block:: lua
function Info(msg)
core.log(core.info, msg)
end
..
.. js:function:: core.Warning(msg)
**context**: body, init, task, action, sample-fetch, converter
:param string msg: The log content.
:see: :js:func:`core.log`
.. code-block:: lua
function Warning(msg)
core.log(core.warning, msg)
end
..
.. js:function:: core.Alert(msg)
**context**: body, init, task, action, sample-fetch, converter
:param string msg: The log content.
:see: :js:func:`core.log`
.. code-block:: lua
function Alert(msg)
core.log(core.alert, msg)
end
..
.. js:function:: core.add_acl(name, key)
**context**: init, task, action, sample-fetch, converter
Add the ACL *key* in the ACLs list referenced by *name*.
:param string name: the name that reference the ACL entries.
:param string key: the key which will be added.
.. js:function:: core.del_acl(name, key)
**context**: init, task, action, sample-fetch, converter
Delete the ACL entry referenced by the key *key* in the list of ACLs
referenced by *name*.
:param string name: the name that reference the ACL entries.
:param string key: the key which will be deleted.
.. js:function:: core.del_map(name, key)
**context**: init, task, action, sample-fetch, converter
Delete the map entry indexed with the specified key in the list of maps
referenced by his name.
:param string name: the name that reference the map entries.
:param string key: the key which will be deleted.
.. js:function:: core.get_info()
**context**: body, init, task, action, sample-fetch, converter
Returns HAProxy core information. We can find information like the uptime,
the pid, memory pool usage, tasks number, ...
This information is also returned by the management socket via the command
"show info". See the management socket documentation for more information
about the content of these variables.
:returns: an array of values.
.. js:function:: core.get_var()
**context**: body, init, task, action, sample-fetch, converter
Returns data stored in the variable <var> converter in Lua type.
This is limited to "proc." scoped variables.
:param string var: The variable name in "proc." scope according with the
HAProxy variable syntax.
.. js:function:: core.now()
**context**: body, init, task, action
This function returns the current time. The time returned is fixed by the
HAProxy core and assures than the hour will be monotonic and that the system
call 'gettimeofday' will not be called too. The time is refreshed between each
Lua execution or resume, so two consecutive call to the function "now" will
probably returns the same result.
:returns: a table which contains two entries "sec" and "usec". "sec"
contains the current at the epoch format, and "usec" contains the
current microseconds.
.. js:function:: core.http_date(date)
**context**: body, init, task, action
This function take a string representing http date, and returns an integer
containing the corresponding date with a epoch format. A valid http date
me respect the format IMF, RFC850 or ASCTIME.
:param string date: a date http-date formatted
:returns: integer containing epoch date
:see: :js:func:`core.imf_date`.
:see: :js:func:`core.rfc850_date`.
:see: :js:func:`core.asctime_date`.
:see: https://tools.ietf.org/html/rfc7231#section-7.1.1.1
.. js:function:: core.imf_date(date)
**context**: body, init, task, action
This function take a string representing IMF date, and returns an integer
containing the corresponding date with a epoch format.
:param string date: a date IMF formatted
:returns: integer containing epoch date
:see: https://tools.ietf.org/html/rfc7231#section-7.1.1.1
The IMF format is like this:
.. code-block:: text
Sun, 06 Nov 1994 08:49:37 GMT
..
.. js:function:: core.rfc850_date(date)
**context**: body, init, task, action
This function take a string representing RFC850 date, and returns an integer
containing the corresponding date with a epoch format.
:param string date: a date RFC859 formatted
:returns: integer containing epoch date
:see: https://tools.ietf.org/html/rfc7231#section-7.1.1.1
The RFC850 format is like this:
.. code-block:: text
Sunday, 06-Nov-94 08:49:37 GMT
..
.. js:function:: core.asctime_date(date)
**context**: body, init, task, action
This function take a string representing ASCTIME date, and returns an integer
containing the corresponding date with a epoch format.
:param string date: a date ASCTIME formatted
:returns: integer containing epoch date
:see: https://tools.ietf.org/html/rfc7231#section-7.1.1.1
The ASCTIME format is like this:
.. code-block:: text
Sun Nov 6 08:49:37 1994
..
.. js:function:: core.msleep(milliseconds)
**context**: body, init, task, action
The `core.msleep()` stops the Lua execution between specified milliseconds.
:param integer milliseconds: the required milliseconds.
.. js:function:: core.register_action(name, actions, func [, nb_args])
**context**: body
Register a Lua function executed as action. All the registered action can be
used in HAProxy with the prefix "lua.". An action gets a TXN object class as
input.
:param string name: is the name of the action.
:param table actions: is a table of string describing the HAProxy actions
facilities where to expose the new action. Expected facilities are:
'tcp-req', 'tcp-res', 'http-req', 'http-res', 'http-after-res'.
:param function func: is the Lua function called to work as an action.
:param integer nb_args: is the expected number of argument for the action.
By default the value is 0.
The prototype of the Lua function used as argument is:
.. code-block:: lua
function(txn [, arg1 [, arg2]])
..
* **txn** (:ref:`txn_class`): this is a TXN object used for manipulating the
current request or TCP stream.
* **argX**: this is argument provided through the HAProxy configuration file.
Here, an example of action registration. The action just send an 'Hello world'
in the logs.
.. code-block:: lua
core.register_action("hello-world", { "tcp-req", "http-req" }, function(txn)
txn:Info("Hello world")
end)
..
This example code is used in HAProxy configuration like this:
::
frontend tcp_frt
mode tcp
tcp-request content lua.hello-world
frontend http_frt
mode http
http-request lua.hello-world
..
A second example using arguments
.. code-block:: lua
function hello_world(txn, arg)
txn:Info("Hello world for " .. arg)
end
core.register_action("hello-world", { "tcp-req", "http-req" }, hello_world, 2)
..
This example code is used in HAProxy configuration like this:
::
frontend tcp_frt
mode tcp
tcp-request content lua.hello-world everybody
..
.. js:function:: core.register_converters(name, func)
**context**: body
Register a Lua function executed as converter. All the registered converters
can be used in HAProxy with the prefix "lua.". A converter gets a string as
input and returns a string as output. The registered function can take up to 9
values as parameter. All the values are strings.
:param string name: is the name of the converter.
:param function func: is the Lua function called to work as converter.
The prototype of the Lua function used as argument is:
.. code-block:: lua
function(str, [p1 [, p2 [, ... [, p5]]]])
..
* **str** (*string*): this is the input value automatically converted in
string.
* **p1** .. **p5** (*string*): this is a list of string arguments declared in
the HAProxy configuration file. The number of arguments doesn't exceed 5.
The order and the nature of these is conventionally chosen by the
developer.
.. js:function:: core.register_fetches(name, func)
**context**: body
Register a Lua function executed as sample fetch. All the registered sample
fetch can be used in HAProxy with the prefix "lua.". A Lua sample fetch
returns a string as output. The registered function can take up to 9 values as
parameter. All the values are strings.
:param string name: is the name of the sample fetch.
:param function func: is the Lua function called to work as sample fetch.
The prototype of the Lua function used as argument is:
.. code-block:: lua
string function(txn, [p1 [, p2 [, ... [, p5]]]])
..
* **txn** (:ref:`txn_class`): this is the txn object associated with the
current request.
* **p1** .. **p5** (*string*): this is a list of string arguments declared in
the HAProxy configuration file. The number of arguments doesn't exceed 5.
The order and the nature of these is conventionally chosen by the
developer.
* **Returns**: A string containing some data, or nil if the value cannot be
returned now.
lua example code:
.. code-block:: lua
core.register_fetches("hello", function(txn)
return "hello"
end)
..
HAProxy example configuration:
::
frontend example
http-request redirect location /%[lua.hello]
.. js:function:: core.register_filter(name, Flt, func)
**context**: body
Register a Lua function used to declare a filter. All the registered filters
can by used in HAProxy with the prefix "lua.".
:param string name: is the name of the filter.
:param table Flt: is a Lua class containing the filter definition (id, flags,
callbacks).
:param function func: is the Lua function called to create the Lua filter.
The prototype of the Lua function used as argument is:
.. code-block:: lua
function(flt, args)
..
* **flt** : Is a filter object based on the class provided in
:js:func:`core.register_filter()` function.
* **args**: Is a table of strings containing all arguments provided through
the HAProxy configuration file, on the filter line.
It must return the filter to use or nil to ignore it. Here, an example of
filter registration.
.. code-block:: lua
core.register_filter("my-filter", MyFilter, function(flt, args)
flt.args = args -- Save arguments
return flt
end)
..
This example code is used in HAProxy configuration like this:
::
frontend http
mode http
filter lua.my-filter arg1 arg2 arg3
..
:see: :js:class:`Filter`
.. js:function:: core.register_service(name, mode, func)
**context**: body
Register a Lua function executed as a service. All the registered services
can be used in HAProxy with the prefix "lua.". A service gets an object class
as input according with the required mode.
:param string name: is the name of the service.
:param string mode: is string describing the required mode. Only 'tcp' or
'http' are allowed.
:param function func: is the Lua function called to work as service.
The prototype of the Lua function used as argument is:
.. code-block:: lua
function(applet)
..
* **applet** *applet* will be a :ref:`applettcp_class` or a
:ref:`applethttp_class`. It depends the type of registered applet. An applet
registered with the 'http' value for the *mode* parameter will gets a
:ref:`applethttp_class`. If the *mode* value is 'tcp', the applet will gets
a :ref:`applettcp_class`.
.. warning::
Applets of type 'http' cannot be called from 'tcp-*' rulesets. Only the
'http-*' rulesets are authorized, this means that is not possible to call
a HTTP applet from a proxy in tcp mode. Applets of type 'tcp' can be
called from anywhere.
Here, an example of service registration. The service just send an
'Hello world' as an http response.
.. code-block:: lua
core.register_service("hello-world", "http", function(applet)
local response = "Hello World !"
applet:set_status(200)
applet:add_header("content-length", string.len(response))
applet:add_header("content-type", "text/plain")
applet:start_response()
applet:send(response)
end)
..
This example code is used in HAProxy configuration like this:
::
frontend example
http-request use-service lua.hello-world
.. js:function:: core.register_init(func)
**context**: body
Register a function executed after the configuration parsing. This is useful
to check any parameters.
:param function func: is the Lua function called to work as initializer.
The prototype of the Lua function used as argument is:
.. code-block:: lua
function()
..
It takes no input, and no output is expected.
.. js:function:: core.register_task(func[, arg1[, arg2[, ...[, arg4]]]])
**context**: body, init, task, action, sample-fetch, converter, event
Register and start independent task. The task is started when the HAProxy
main scheduler starts. For example this type of tasks can be executed to
perform complex health checks.
:param function func: is the Lua function called to work as an async task.
Up to 4 optional arguments (all types supported) may be passed to the
function. (They will be passed as-is to the task function)
The prototype of the Lua function used as argument is:
.. code-block:: lua
function([arg1[, arg2[, ...[, arg4]]]])
..
It takes up to 4 optional arguments (provided when registering), and no
output is expected.
See also :js:func:`core.queue` to dynamically pass data between main context
and tasks or even between tasks.
.. js:function:: core.register_cli([path], usage, func)
**context**: body
Register a custom cli that will be available from haproxy stats socket.
:param array path: is the sequence of word for which the cli execute the Lua
binding.
:param string usage: is the usage message displayed in the help.
:param function func: is the Lua function called to handle the CLI commands.
The prototype of the Lua function used as argument is:
.. code-block:: lua
function(AppletTCP, [arg1, [arg2, [...]]])
..
I/O are managed with the :ref:`applettcp_class` object. Args are given as
parameter. The args embed the registered path. If the path is declared like
this:
.. code-block:: lua
core.register_cli({"show", "ssl", "stats"}, "Display SSL stats..", function(applet, arg1, arg2, arg3, arg4, arg5)
end)
..
And we execute this in the prompt:
.. code-block:: text
> prompt
> show ssl stats all
..
Then, arg1, arg2 and arg3 will contains respectively "show", "ssl" and
"stats".
arg4 will contain "all". arg5 contains nil.
.. js:function:: core.set_nice(nice)
**context**: task, action, sample-fetch, converter
Change the nice of the current task or current session.
:param integer nice: the nice value, it must be between -1024 and 1024.
.. js:function:: core.set_map(name, key, value)
**context**: init, task, action, sample-fetch, converter
Set the value *value* associated to the key *key* in the map referenced by
*name*.
:param string name: the Map reference
:param string key: the key to set or replace
:param string value: the associated value
.. js:function:: core.sleep(int seconds)
**context**: body, init, task, action
The `core.sleep()` functions stop the Lua execution between specified seconds.
:param integer seconds: the required seconds.
.. js:function:: core.tcp()
**context**: init, task, action
This function returns a new object of a *socket* class.
:returns: A :ref:`socket_class` object.
.. js:function:: core.httpclient()
**context**: init, task, action
This function returns a new object of a *httpclient* class.
:returns: A :ref:`httpclient_class` object.
.. js:function:: core.concat()
**context**: body, init, task, action, sample-fetch, converter
This function returns a new concat object.
:returns: A :ref:`concat_class` object.
.. js:function:: core.queue()
**context**: body, init, task, event, action, sample-fetch, converter
This function returns a new queue object.
:returns: A :ref:`queue_class` object.
.. js:function:: core.done(data)
**context**: body, init, task, action, sample-fetch, converter
:param any data: Return some data for the caller. It is useful with
sample-fetches and sample-converters.
Immediately stops the current Lua execution and returns to the caller which
may be a sample fetch, a converter or an action and returns the specified
value (ignored for actions and init). It is used when the LUA process finishes
its work and wants to give back the control to HAProxy without executing the
remaining code. It can be seen as a multi-level "return".
.. js:function:: core.yield()
**context**: task, action, sample-fetch, converter
Give back the hand at the HAProxy scheduler. It is used when the LUA
processing consumes a lot of processing time.
.. js:function:: core.parse_addr(address)
**context**: body, init, task, action, sample-fetch, converter
:param network: is a string describing an ipv4 or ipv6 address and optionally
its network length, like this: "127.0.0.1/8" or "aaaa::1234/32".
:returns: a userdata containing network or nil if an error occurs.
Parse ipv4 or ipv6 addresses and its facultative associated network.
.. js:function:: core.match_addr(addr1, addr2)
**context**: body, init, task, action, sample-fetch, converter
:param addr1: is an address created with "core.parse_addr".
:param addr2: is an address created with "core.parse_addr".
:returns: boolean, true if the network of the addresses match, else returns
false.
Match two networks. For example "127.0.0.1/32" matches "127.0.0.0/8". The
order of network is not important.
.. js:function:: core.tokenize(str, separators [, noblank])
**context**: body, init, task, action, sample-fetch, converter
This function is useful for tokenizing an entry, or splitting some messages.
:param string str: The string which will be split.
:param string separators: A string containing a list of separators.
:param boolean noblank: Ignore empty entries.
:returns: an array of string.
For example:
.. code-block:: lua
local array = core.tokenize("This function is useful, for tokenizing an entry.", "., ", true)
print_r(array)
..
Returns this array:
.. code-block:: text
(table) table: 0x21c01e0 [
1: (string) "This"
2: (string) "function"
3: (string) "is"
4: (string) "useful"
5: (string) "for"
6: (string) "tokenizing"
7: (string) "an"
8: (string) "entry"
]
..
.. js:function:: core.event_sub(event_types, func)
**context**: body, init, task, action, sample-fetch, converter
Register a function that will be called on specific system events.
:param array event_types: array of string containing the event types you want
to subscribe to
:param function func: is the Lua function called when one of the subscribed
events occur.
:returns: A :ref:`event_sub_class` object.
:see: :js:func:`Server.event_sub()`.
List of available event types :
**SERVER** Family:
* **SERVER_ADD**: when a server is added
* **SERVER_DEL**: when a server is removed
* **SERVER_DOWN**: when a server state goes from UP to DOWN
* **SERVER_UP**: when a server state goes from DOWN to UP
* **SERVER_STATE**: when a server state changes
* **SERVER_ADMIN**: when a server administrative state changes
* **SERVER_CHECK**: when a server's check status change is reported.
Be careful when subscribing to this type since many events might be
generated.
.. Note::
Use **SERVER** in **event_types** to subscribe to all server events types
at once. Note that this should only be used for testing purposes since a
single event source could result in multiple events types being generated.
(e.g.: SERVER_STATE will always be generated for each SERVER_DOWN or
SERVER_UP)
The prototype of the Lua function used as argument is:
.. code-block:: lua
function(event, event_data, sub, when)
..
* **event** (*string*): the event type (one of the **event_types** specified
when subscribing)
* **event_data**: specific to each event family (For **SERVER** family,
a :ref:`server_event_class` object)
* **sub**: class to manage the subscription from within the event
(a :ref:`event_sub_class` object)
* **when**: timestamp corresponding to the date when the event was generated.
It is an integer representing the number of seconds elapsed since Epoch.
It may be provided as optional argument to `os.date()` lua function to
convert it to a string according to a given format string.
.. Warning::
The callback function will only be scheduled on the very same thread that
performed the subscription.
Moreover, each thread treats events sequentially. It means that if you
have, let's say SERVER_UP followed by a SERVER_DOWN in a short timelapse,
then the cb function will first be called with SERVER_UP, and once it's
done handling the event, the cb function will be called again with
SERVER_DOWN.
This is to ensure event consistency when it comes to logging / triggering
logic from lua.
Your lua cb function may yield if needed, but you're pleased to process the
event as fast as possible to prevent the event queue from growing up,
depending on the event flow that is expected for the given subscription.
To prevent abuses, if the event queue for the current subscription goes
over a certain amount of unconsumed events, the subscription will pause
itself automatically for as long as it takes for your handler to catch up.
This would lead to events being missed, so an error will be reported in the
logs to warn you about that.
This is not something you want to let happen too often, it may indicate
that you subscribed to an event that is occurring too frequently or/and
that your callback function is too slow to keep up the pace and you should
review it.
If you want to do some parallel processing because your callback functions
are slow: you might want to create subtasks from lua using
:js:func:`core.register_task()` from within your callback function to
perform the heavy job in a dedicated task and allow remaining events to be
processed more quickly.
.. js:function:: core.disable_legacy_mailers()
**LEGACY**
**context**: body, init
Disable the sending of email alerts through the legacy email sending
function when mailers are used in the configuration.
Use this when sending email alerts directly from lua.
:see: :js:func:`Proxy.get_mailers()`
.. _proxy_class:
Proxy class
============
.. js:class:: Proxy
This class provides a way for manipulating proxy and retrieving information
like statistics.
.. js:attribute:: Proxy.name
Contain the name of the proxy.
.. warning::
This attribute is now deprecated and will eventually be removed.
Please use :js:func:`Proxy.get_name()` function instead.
.. js:function:: Proxy.get_name()
Returns the name of the proxy.
.. js:attribute:: Proxy.uuid
Contain the unique identifier of the proxy.
.. warning::
This attribute is now deprecated and will eventually be removed.
Please use :js:func:`Proxy.get_uuid()` function instead.
.. js:function:: Proxy.get_uuid()
Returns the unique identifier of the proxy.
.. js:attribute:: Proxy.servers
Contain a table with the attached servers. The table is indexed by server
name, and each server entry is an object of type :ref:`server_class`.
.. js:attribute:: Proxy.stktable
Contains a stick table object of type :ref:`sticktable_class` attached to the
proxy.
.. js:attribute:: Proxy.listeners
Contain a table with the attached listeners. The table is indexed by listener
name, and each each listeners entry is an object of type
:ref:`listener_class`.
.. js:function:: Proxy.pause(px)
Pause the proxy. See the management socket documentation for more information.
:param class_proxy px: A :ref:`proxy_class` which indicates the manipulated
proxy.
.. js:function:: Proxy.resume(px)
Resume the proxy. See the management socket documentation for more
information.
:param class_proxy px: A :ref:`proxy_class` which indicates the manipulated
proxy.
.. js:function:: Proxy.stop(px)
Stop the proxy. See the management socket documentation for more information.
:param class_proxy px: A :ref:`proxy_class` which indicates the manipulated
proxy.
.. js:function:: Proxy.shut_bcksess(px)
Kill the session attached to a backup server. See the management socket
documentation for more information.
:param class_proxy px: A :ref:`proxy_class` which indicates the manipulated
proxy.
.. js:function:: Proxy.get_cap(px)
Returns a string describing the capabilities of the proxy.
:param class_proxy px: A :ref:`proxy_class` which indicates the manipulated
proxy.
:returns: a string "frontend", "backend", "proxy" or "ruleset".
.. js:function:: Proxy.get_mode(px)
Returns a string describing the mode of the current proxy.
:param class_proxy px: A :ref:`proxy_class` which indicates the manipulated
proxy.
:returns: a string "tcp", "http", "syslog" or "unknown"
.. js:function:: Proxy.get_srv_act(px)
Returns the number of current active servers for the current proxy that are
eligible for LB.
:param class_proxy px: A :ref:`proxy_class` which indicates the manipulated
proxy.
:returns: an integer
.. js:function:: Proxy.get_srv_bck(px)
Returns the number backup servers for the current proxy that are eligible
for LB.
:param class_proxy px: A :ref:`proxy_class` which indicates the manipulated
proxy.
:returns: an integer
.. js:function:: Proxy.get_stats(px)
Returns a table containing the proxy statistics. The statistics returned are
not the same if the proxy is frontend or a backend.
:param class_proxy px: A :ref:`proxy_class` which indicates the manipulated
proxy.
:returns: a key/value table containing stats
.. js:function:: Proxy.get_mailers(px)
**LEGACY**
Returns a table containing mailers config for the current proxy or nil
if mailers are not available for the proxy.
:param class_proxy px: A :ref:`proxy_class` which indicates the manipulated
proxy.
:returns: a :ref:`proxy_mailers_class` containing proxy mailers config
.. _proxy_mailers_class:
ProxyMailers class
==================
**LEGACY**
.. js:class:: ProxyMailers
This class provides mailers config for a given proxy.
If sending emails directly from lua, please consider
:js:func:`core.disable_legacy_mailers()` to disable the email sending from
haproxy. (Or email alerts will be sent twice...)
.. js:attribute:: ProxyMailers.track_server_health
Boolean set to true if the option "log-health-checks" is configured on
the proxy, meaning that all server checks event should trigger email alerts.
.. js:attribute:: ProxyMailers.log_level
An integer, the maximum log level that triggers email alerts. It is a number
between 0 and 7 as defined by option "email-alert level".
.. js:attribute:: ProxyMailers.mailservers
An array containing the list of mail servers that should receive email alerts.
Each array entry is a name:desc pair where desc represents the full server
address (including port) as described in haproxy's configuration file.
.. js:attribute:: ProxyMailers.mailservers_timeout
An integer representing the maximum time in milliseconds to wait for the
email to be sent. See "timeout mail" directive from "mailers" section in
haproxy configuration file.
.. js:attribute:: ProxyMailers.smtp_hostname
A string containing the hostname to use for the SMTP transaction.
(option "email-alert myhostname")
.. js:attribute:: ProxyMailers.smtp_from
A string containing the "MAIL FROM" address to use for the SMTP transaction.
(option "email-alert from")
.. js:attribute:: ProxyMailers.smtp_to
A string containing the "RCPT TO" address to use for the SMTP transaction.
(option "email-alert to")
.. _server_class:
Server class
============
.. js:class:: Server
This class provides a way for manipulating servers and retrieving information.
.. js:attribute:: Server.name
Contain the name of the server.
.. warning::
This attribute is now deprecated and will eventually be removed.
Please use :js:func:`Server.get_name()` function instead.
.. js:function:: Server.get_name(sv)
Returns the name of the server.
.. js:attribute:: Server.puid
Contain the proxy unique identifier of the server.
.. warning::
This attribute is now deprecated and will eventually be removed.
Please use :js:func:`Server.get_puid()` function instead.
.. js:function:: Server.get_puid(sv)
Returns the proxy unique identifier of the server.
.. js:function:: Server.get_rid(sv)
Returns the rid (revision ID) of the server.
It is an unsigned integer that is set upon server creation. Value is derived
from a global counter that starts at 0 and is incremented each time one or
multiple server deletions are followed by a server addition (meaning that
old name/id reuse could occur).
Combining server name/id with server rid yields a process-wide unique
identifier.
.. js:function:: Server.is_draining(sv)
Return true if the server is currently draining sticky connections.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:returns: a boolean
.. js:function:: Server.is_backup(sv)
Return true if the server is a backup server
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:returns: a boolean
.. js:function:: Server.is_dynamic(sv)
Return true if the server was instantiated at runtime (e.g.: from the cli)
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:returns: a boolean
.. js:function:: Server.get_cur_sess(sv)
Return the number of currently active sessions on the server
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:returns: an integer
.. js:function:: Server.get_pend_conn(sv)
Return the number of pending connections to the server
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:returns: an integer
.. js:function:: Server.set_maxconn(sv, weight)
Dynamically change the maximum connections of the server. See the management
socket documentation for more information about the format of the string.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:param string maxconn: A string describing the server maximum connections.
.. js:function:: Server.get_maxconn(sv, weight)
This function returns an integer representing the server maximum connections.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:returns: an integer.
.. js:function:: Server.set_weight(sv, weight)
Dynamically change the weight of the server. See the management socket
documentation for more information about the format of the string.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:param string weight: A string describing the server weight.
.. js:function:: Server.get_weight(sv)
This function returns an integer representing the server weight.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:returns: an integer.
.. js:function:: Server.set_addr(sv, addr[, port])
Dynamically change the address of the server. See the management socket
documentation for more information about the format of the string.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:param string addr: A string describing the server address.
.. js:function:: Server.get_addr(sv)
Returns a string describing the address of the server.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:returns: A string
.. js:function:: Server.get_stats(sv)
Returns server statistics.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:returns: a key/value table containing stats
.. js:function:: Server.get_proxy(sv)
Returns the parent proxy to which the server belongs.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:returns: a :ref:`proxy_class` or nil if not available
.. js:function:: Server.shut_sess(sv)
Shutdown all the sessions attached to the server. See the management socket
documentation for more information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.set_drain(sv)
Drain sticky sessions. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.set_maint(sv)
Set maintenance mode. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.set_ready(sv)
Set normal mode. See the management socket documentation for more information
about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.check_enable(sv)
Enable health checks. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.check_disable(sv)
Disable health checks. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.check_force_up(sv)
Force health-check up. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.check_force_nolb(sv)
Force health-check nolb mode. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.check_force_down(sv)
Force health-check down. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.agent_enable(sv)
Enable agent check. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.agent_disable(sv)
Disable agent check. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.agent_force_up(sv)
Force agent check up. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.agent_force_down(sv)
Force agent check down. See the management socket documentation for more
information about this function.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
.. js:function:: Server.tracking(sv)
Check if the current server is tracking another server.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:returns: A :ref:`server_class` which indicates the tracked server or nil if
the server doesn't track another one.
.. js:function:: Server.get_trackers(sv)
Check if the current server is being tracked by other servers.
:param class_server sv: A :ref:`server_class` which indicates the manipulated
server.
:returns: An array of :ref:`server_class` which indicates the tracking
servers (might be empty)
.. js:function:: Server.event_sub(sv, event_types, func)
Register a function that will be called on specific server events.
It works exactly like :js:func:`core.event_sub()` except that the subscription
will be performed within the server dedicated subscription list instead of the
global one.
(Your callback function will only be called for server events affecting sv)
See :js:func:`core.event_sub()` for function usage.
A key advantage to using :js:func:`Server.event_sub()` over
:js:func:`core.event_sub()` for servers is that :js:func:`Server.event_sub()`
allows you to be notified for servers events of a single server only.
It removes the needs for extra filtering in your callback function if you only
care about a single server, and also prevents useless wakeups.
For instance, if you want to be notified for UP/DOWN events on a given set of
servers, it is recommended to perform multiple per-server subscriptions since
it will be more efficient that doing a single global subscription that will
filter the received events.
Unless you really want to be notified for servers events of ALL servers of
course, which could make sense given you setup but should be avoided if you
have an important number of servers as it will add a significant load on your
haproxy process in case of multiple servers state change in a short amount of
time.
.. Note::
You may also combine :js:func:`core.event_sub()` with
:js:func:`Server.event_sub()`.
Also, don't forget that you can use :js:func:`core.register_task()` from
your callback function if needed. (ie: parallel work)
Here is a working example combining :js:func:`core.event_sub()` with
:js:func:`Server.event_sub()` and :js:func:`core.register_task()`
(This only serves as a demo, this is not necessarily useful to do so)
.. code-block:: lua
core.event_sub({"SERVER_ADD"}, function(event, data, sub)
-- in the global event handler
if data["reference"] ~= nil then
print("Tracking new server: ", data["name"])
data["reference"]:event_sub({"SERVER_UP", "SERVER_DOWN"}, function(event, data, sub)
-- in the per-server event handler
if data["reference"] ~= nil then
core.register_task(function(server)
-- subtask to perform some async work (e.g.: HTTP API calls, sending emails...)
print("ASYNC: SERVER ", server:get_name(), " is ", event == "SERVER_UP" and "UP" or "DOWN")
end, data["reference"])
end
end)
end
end)
..
In this example, we will first track global server addition events.
For each newly added server ("add server" on the cli), we will register a
UP/DOWN server subscription.
Then, the callback function will schedule the event handling in an async
subtask which will receive the server reference as an argument.
.. _listener_class:
Listener class
==============
.. js:function:: Listener.get_stats(ls)
Returns server statistics.
:param class_listener ls: A :ref:`listener_class` which indicates the
manipulated listener.
:returns: a key/value table containing stats
.. _event_sub_class:
EventSub class
==============
.. js:function:: EventSub.unsub()
End the subscription, the callback function will not be called again.
.. _server_event_class:
ServerEvent class
=================
.. js:class:: ServerEvent
This class is provided with every **SERVER** events.
See :js:func:`core.event_sub()` for more info.
.. js:attribute:: ServerEvent.name
Contains the name of the server.
.. js:attribute:: ServerEvent.puid
Contains the proxy-unique uid of the server
.. js:attribute:: ServerEvent.rid
Contains the revision ID of the server
.. js:attribute:: ServerEvent.proxy_name
Contains the name of the proxy to which the server belongs
.. js:attribute:: ServerEvent.proxy_uuid
Contains the uuid of the proxy to which the server belongs
.. js:attribute:: ServerEvent.reference
Reference to the live server (A :ref:`server_class`).
.. Warning::
Not available if the server was removed in the meantime.
(Will never be set for SERVER_DEL event since the server does not exist
anymore)
.. js:attribute:: ServerEvent.state
A :ref:`server_event_state_class`
.. Note::
Only available for SERVER_STATE event
.. js:attribute:: ServerEvent.admin
A :ref:`server_event_admin_class`
.. Note::
Only available for SERVER_ADMIN event
.. js:attribute:: ServerEvent.check
A :ref:`server_event_checkres_class`
.. Note::
Only available for SERVER_CHECK event
.. _server_event_checkres_class:
ServerEventCheckRes class
=========================
.. js:class:: ServerEventCheckRes
This class describes the result of a server's check.
.. js:attribute:: ServerEventCheckRes.result
Effective check result.
Check result is a string and will be set to one of the following values:
- "FAILED": the check failed
- "PASSED": the check succeeded
- "CONDPASS": the check conditionally passed
.. js:attribute:: ServerEventCheckRes.agent
Boolean set to true if the check is an agent check.
Else it is a health check.
.. js:attribute:: ServerEventCheckRes.duration
Check's duration in milliseconds
.. js:attribute:: ServerEventCheckRes.reason
Check's status. An array containing three fields:
- **short**: a string representing check status short name
- **desc**: a string representing check status description
- **code**: an integer, this extra information is provided for checks
that went through the data analysis stage (>= layer 5)
.. js:attribute:: ServerEventCheckRes.health
An array containing values about check's health (integers):
- **cur**: current health counter:
- 0 to (**rise** - 1) = BAD
- **rise** to (**rise** + **fall** - 1) = GOOD
- **rise**: server will be considered as operational after **rise**
consecutive successful checks
- **fall**: server will be considered as dead after **fall** consecutive
unsuccessful checks
.. _server_event_state_class:
ServerEventState class
======================
.. js:class:: ServerEventState
This class contains additional info related to **SERVER_STATE** event.
.. js:attribute:: ServerEventState.admin
Boolean set to true if the server state change is due to an administrative
change. Else it is an operational change.
.. js:attribute:: ServerEventState.check
A :ref:`server_event_checkres_class`, provided if the state change is
due to a server check (must be an operational change).
.. js:attribute:: ServerEventState.cause
Printable state change cause. Might be empty.
.. js:attribute:: ServerEventState.new_state
New server state due to operational or admin change.
It is a string that can be any of the following values:
- "STOPPED": The server is down
- "STOPPING": The server is up but soft-stopping
- "STARTING": The server is warming up
- "RUNNING": The server is fully up
.. js:attribute:: ServerEventState.old_state
Previous server state prior to the operational or admin change.
Can be any value described in **new_state**, but they should differ.
.. js:attribute:: ServerEventState.requeued
Number of connections that were requeued due to the server state change.
For a server going DOWN: it is the number of pending server connections
that are requeued to the backend (such connections will be redispatched
to any server that is suitable according to the configured load balancing
algorithm).
For a server doing UP: it is the number of pending connections on the
backend that may be redispatched to the server according to the load
balancing algorithm that is in use.
.. _server_event_admin_class:
ServerEventAdmin class
======================
.. js:class:: ServerEventAdmin
This class contains additional info related to **SERVER_ADMIN** event.
.. js:attribute:: ServerEventAdmin.cause
Printable admin state change cause. Might be empty.
.. js:attribute:: ServerEventAdmin.new_admin
New server admin state due to the admin change.
It is an array of string containing a composition of following values:
- "**MAINT**": server is in maintenance mode
- "FMAINT": server is in forced maintenance mode (MAINT is also set)
- "IMAINT": server is in inherited maintenance mode (MAINT is also set)
- "RMAINT": server is in resolve maintenance mode (MAINT is also set)
- "CMAINT": server is in config maintenance mode (MAINT is also set)
- "**DRAIN**": server is in drain mode
- "FDRAIN": server is in forced drain mode (DRAIN is also set)
- "IDRAIN": server is in inherited drain mode (DRAIN is also set)
.. js:attribute:: ServerEventAdmin.old_admin
Previous server admin state prior to the admin change.
Values are presented as in **new_admin**, but they should differ.
(Comparing old and new helps to find out the change(s))
.. js:attribute:: ServerEventAdmin.requeued
Same as :js:attr:`ServerEventState.requeued` but when the requeue is due to
the server administrative state change.
.. _queue_class:
Queue class
===========
.. js:class:: Queue
This class provides a generic FIFO storage mechanism that may be shared
between multiple lua contexts to easily pass data between them, as stock
Lua doesn't provide easy methods for passing data between multiple coroutines.
inter-task example:
.. code-block:: lua
-- script wide shared queue
local queue = core.queue()
-- master task
core.register_task(function()
-- send the date every second
while true do
queue:push(os.date("%c", core.now().sec))
core.sleep(1)
end
end)
-- worker task
core.register_task(function()
while true do
-- print the date sent by master
print(queue:pop_wait())
end
end)
..
Of course, queue may also be used as a local storage mechanism.
Use :js:func:`core.queue` to get a new Queue object.
.. js:function:: Queue.size(queue)
This function returns the number of items within the Queue.
:param class_queue queue: A :ref:`queue_class` to the current queue
.. js:function:: Queue.push(queue, item)
This function pushes the item (may be of any type) to the queue.
Pushed item cannot be nil or invalid, or an error will be thrown.
:param class_queue queue: A :ref:`queue_class` to the current queue
:returns: boolean true for success and false for error
.. js:function:: Queue.pop(queue)
This function immediately tries to pop an item from the queue.
It returns nil of no item is available at the time of the call.
:param class_queue queue: A :ref:`queue_class` to the current queue
:returns: the item at the top of the stack (any type) or nil if no items
.. js:function:: Queue.pop_wait(queue)
**context**: task
This is an alternative to pop() that may be used within task contexts.
The call waits for data if no item is currently available. This may be
useful when used in a while loop to prevent cpu waste.
Note that this requires yielding, thus it is only available within contexts
that support yielding (mainly task context).
:param class_queue queue: A :ref:`queue_class` to the current queue
:returns: the item at the top of the stack (any type) or nil in case of error
.. _concat_class:
Concat class
============
.. js:class:: Concat
This class provides a fast way for string concatenation. The way using native
Lua concatenation like the code below is slow for some reasons.
.. code-block:: lua
str = "string1"
str = str .. ", string2"
str = str .. ", string3"
..
For each concatenation, Lua:
- allocates memory for the result,
- catenates the two string copying the strings in the new memory block,
- frees the old memory block containing the string which is no longer used.
This process does many memory move, allocation and free. In addition, the
memory is not really freed, it is just marked as unused and waits for the
garbage collector.
The Concat class provides an alternative way to concatenate strings. It uses
the internal Lua mechanism (it does not allocate memory), but it doesn't copy
the data more than once.
On my computer, the following loops spends 0.2s for the Concat method and
18.5s for the pure Lua implementation. So, the Concat class is about 1000x
faster than the embedded solution.
.. code-block:: lua
for j = 1, 100 do
c = core.concat()
for i = 1, 20000 do
c:add("#####")
end
end
..
.. code-block:: lua
for j = 1, 100 do
c = ""
for i = 1, 20000 do
c = c .. "#####"
end
end
..
.. js:function:: Concat.add(concat, string)
This function adds a string to the current concatenated string.
:param class_concat concat: A :ref:`concat_class` which contains the currently
built string.
:param string string: A new string to concatenate to the current built
string.
.. js:function:: Concat.dump(concat)
This function returns the concatenated string.
:param class_concat concat: A :ref:`concat_class` which contains the currently
built string.
:returns: the concatenated string
.. _fetches_class:
Fetches class
=============
.. js:class:: Fetches
This class contains a lot of internal HAProxy sample fetches. See the
HAProxy "configuration.txt" documentation for more information.
(chapters 7.3.2 to 7.3.6)
.. warning::
some sample fetches are not available in some context. These limitations
are specified in this documentation when they're useful.
:see: :js:attr:`TXN.f`
:see: :js:attr:`TXN.sf`
Fetches are useful to:
* get system time,
* get environment variable,
* get random numbers,
* know backend status like the number of users in queue or the number of
connections established,
* get client information like ip source or destination,
* deal with stick tables,
* fetch established SSL information,
* fetch HTTP information like headers or method.
.. code-block:: lua
function action(txn)
-- Get source IP
local clientip = txn.f:src()
end
..
.. _converters_class:
Converters class
================
.. js:class:: Converters
This class contains a lot of internal HAProxy sample converters. See the
HAProxy documentation "configuration.txt" for more information about her
usage. Its the chapter 7.3.1.
:see: :js:attr:`TXN.c`
:see: :js:attr:`TXN.sc`
Converters provides stateful transformation. They are useful to:
* convert input to base64,
* apply hash on input string (djb2, crc32, sdbm, wt6),
* format date,
* json escape,
* extract preferred language comparing two lists,
* turn to lower or upper chars,
* deal with stick tables.
.. _channel_class:
Channel class
=============
.. js:class:: Channel
**context**: action, sample-fetch, convert, filter
HAProxy uses two buffers for the processing of the requests. The first one is
used with the request data (from the client to the server) and the second is
used for the response data (from the server to the client).
Each buffer contains two types of data. The first type is the incoming data
waiting for a processing. The second part is the outgoing data already
processed. Usually, the incoming data is processed, after it is tagged as
outgoing data, and finally it is sent. The following functions provides tools
for manipulating these data in a buffer.
The following diagram shows where the channel class function are applied.
.. image:: _static/channel.png
.. warning::
It is not possible to read from the response in request action, and it is
not possible to read from the request channel in response action.
.. warning::
It is forbidden to alter the Channels buffer from HTTP contexts. So only
:js:func:`Channel.input`, :js:func:`Channel.output`,
:js:func:`Channel.may_recv`, :js:func:`Channel.is_full` and
:js:func:`Channel.is_resp` can be called from a HTTP context.
All the functions provided by this class are available in the
**sample-fetches**, **actions** and **filters** contexts. For **filters**,
incoming data (offset and length) are relative to the filter. Some functions
may yield, but only for **actions**. Yield is not possible for
**sample-fetches**, **converters** and **filters**.
.. js:function:: Channel.append(channel, string)
This function copies the string **string** at the end of incoming data of the
channel buffer. The function returns the copied length on success or -1 if
data cannot be copied.
Same that :js:func:`Channel.insert(channel, string, channel:input())`.
:param class_channel channel: The manipulated Channel.
:param string string: The data to copy at the end of incoming data.
:returns: an integer containing the amount of bytes copied or -1.
.. js:function:: Channel.data(channel [, offset [, length]])
This function returns **length** bytes of incoming data from the channel
buffer, starting at the offset **offset**. The data are not removed from the
buffer.
By default, if no length is provided, all incoming data found, starting at the
given offset, are returned. If **length** is set to -1, the function tries to
retrieve a maximum of data and, if called by an action, it yields if
necessary. It also waits for more data if the requested length exceeds the
available amount of incoming data. Not providing an offset is the same as
setting it to 0. A positive offset is relative to the beginning of incoming
data of the channel buffer while negative offset is relative to the end.
If there is no incoming data and the channel can't receive more data, a 'nil'
value is returned.
:param class_channel channel: The manipulated Channel.
:param integer offset: *optional* The offset in incoming data to start to get
data. 0 by default. May be negative to be relative to the end of incoming
data.
:param integer length: *optional* The expected length of data to retrieve. All
incoming data by default. May be set to -1 to get a maximum of data.
:returns: a string containing the data found or nil.
.. js:function:: Channel.forward(channel, length)
This function forwards **length** bytes of data from the channel buffer. If
the requested length exceeds the available amount of incoming data, and if
called by an action, the function yields, waiting for more data to forward. It
returns the amount of data forwarded.
:param class_channel channel: The manipulated Channel.
:param integer int: The amount of data to forward.
.. js:function:: Channel.input(channel)
This function returns the length of incoming data in the channel buffer. When
called by a filter, this value is relative to the filter.
:param class_channel channel: The manipulated Channel.
:returns: an integer containing the amount of available bytes.
.. js:function:: Channel.insert(channel, string [, offset])
This function copies the string **string** at the offset **offset** in
incoming data of the channel buffer. The function returns the copied length on
success or -1 if data cannot be copied.
By default, if no offset is provided, the string is copied in front of
incoming data. A positive offset is relative to the beginning of incoming data
of the channel buffer while negative offset is relative to their end.
:param class_channel channel: The manipulated Channel.
:param string string: The data to copy into incoming data.
:param integer offset: *optional* The offset in incoming data where to copy
data. 0 by default. May be negative to be relative to the end of incoming
data.
:returns: an integer containing the amount of bytes copied or -1.
.. js:function:: Channel.is_full(channel)
This function returns true if the channel buffer is full.
:param class_channel channel: The manipulated Channel.
:returns: a boolean
.. js:function:: Channel.is_resp(channel)
This function returns true if the channel is the response one.
:param class_channel channel: The manipulated Channel.
:returns: a boolean
.. js:function:: Channel.line(channel [, offset [, length]])
This function parses **length** bytes of incoming data of the channel buffer,
starting at offset **offset**, and returns the first line found, including the
'\\n'. The data are not removed from the buffer. If no line is found, all
data are returned.
By default, if no length is provided, all incoming data, starting at the given
offset, are evaluated. If **length** is set to -1, the function tries to
retrieve a maximum of data and, if called by an action, yields if
necessary. It also waits for more data if the requested length exceeds the
available amount of incoming data. Not providing an offset is the same as
setting it to 0. A positive offset is relative to the beginning of incoming
data of the channel buffer while negative offset is relative to the end.
If there is no incoming data and the channel can't receive more data, a 'nil'
value is returned.
:param class_channel channel: The manipulated Channel.
:param integer offset: *optional* The offset in incoming data to start to
parse data. 0 by default. May be negative to be relative to the end of
incoming data.
:param integer length: *optional* The length of data to parse. All incoming
data by default. May be set to -1 to get a maximum of data.
:returns: a string containing the line found or nil.
.. js:function:: Channel.may_recv(channel)
This function returns true if the channel may still receive data.
:param class_channel channel: The manipulated Channel.
:returns: a boolean
.. js:function:: Channel.output(channel)
This function returns the length of outgoing data of the channel buffer. When
called by a filter, this value is relative to the filter.
:param class_channel channel: The manipulated Channel.
:returns: an integer containing the amount of available bytes.
.. js:function:: Channel.prepend(channel, string)
This function copies the string **string** in front of incoming data of the
channel buffer. The function returns the copied length on success or -1 if
data cannot be copied.
Same that :js:func:`Channel.insert(channel, string, 0)`.
:param class_channel channel: The manipulated Channel.
:param string string: The data to copy in front of incoming data.
:returns: an integer containing the amount of bytes copied or -1.
.. js:function:: Channel.remove(channel [, offset [, length]])
This function removes **length** bytes of incoming data of the channel buffer,
starting at offset **offset**. This function returns number of bytes removed
on success.
By default, if no length is provided, all incoming data, starting at the given
offset, are removed. Not providing an offset is the same as setting it
to 0. A positive offset is relative to the beginning of incoming data of the
channel buffer while negative offset is relative to the end.
:param class_channel channel: The manipulated Channel.
:param integer offset: *optional* The offset in incoming data where to start
to remove data. 0 by default. May be negative to be relative to the end of
incoming data.
:param integer length: *optional* The length of data to remove. All incoming
data by default.
:returns: an integer containing the amount of bytes removed.
.. js:function:: Channel.send(channel, string)
This function requires immediate send of the string **string**. It means the
string is copied at the beginning of incoming data of the channel buffer and
immediately forwarded. Unless if the connection is close, and if called by an
action, this function yields to copy and forward all the string.
:param class_channel channel: The manipulated Channel.
:param string string: The data to send.
:returns: an integer containing the amount of bytes copied or -1.
.. js:function:: Channel.set(channel, string [, offset [, length]])
This function replaces **length** bytes of incoming data of the channel
buffer, starting at offset **offset**, by the string **string**. The function
returns the copied length on success or -1 if data cannot be copied.
By default, if no length is provided, all incoming data, starting at the given
offset, are replaced. Not providing an offset is the same as setting it
to 0. A positive offset is relative to the beginning of incoming data of the
channel buffer while negative offset is relative to the end.
:param class_channel channel: The manipulated Channel.
:param string string: The data to copy into incoming data.
:param integer offset: *optional* The offset in incoming data where to start
the data replacement. 0 by default. May be negative to be relative to the
end of incoming data.
:param integer length: *optional* The length of data to replace. All incoming
data by default.
:returns: an integer containing the amount of bytes copied or -1.
.. js:function:: Channel.dup(channel)
**DEPRECATED**
This function returns all incoming data found in the channel buffer. The data
are not removed from the buffer and can be reprocessed later.
If there is no incoming data and the channel can't receive more data, a 'nil'
value is returned.
:param class_channel channel: The manipulated Channel.
:returns: a string containing all data found or nil.
.. warning::
This function is deprecated. :js:func:`Channel.data()` must be used
instead.
.. js:function:: Channel.get(channel)
**DEPRECATED**
This function returns all incoming data found in the channel buffer and remove
them from the buffer.
If there is no incoming data and the channel can't receive more data, a 'nil'
value is returned.
:param class_channel channel: The manipulated Channel.
:returns: a string containing all the data found or nil.
.. warning::
This function is deprecated. :js:func:`Channel.data()` must be used to
retrieve data followed by a call to :js:func:`Channel:remove()` to remove
data.
.. code-block:: lua
local data = chn:data()
chn:remove(0, data:len())
..
.. js:function:: Channel.getline(channel)
**DEPRECATED**
This function returns the first line found in incoming data of the channel
buffer, including the '\\n'. The returned data are removed from the buffer. If
no line is found, and if called by an action, this function yields to wait for
more data, except if the channel can't receive more data. In this case all
data are returned.
If there is no incoming data and the channel can't receive more data, a 'nil'
value is returned.
:param class_channel channel: The manipulated Channel.
:returns: a string containing the line found or nil.
.. warning::
This function is deprecated. :js:func:`Channel.line()` must be used to
retrieve a line followed by a call to :js:func:`Channel:remove()` to remove
data.
.. code-block:: lua
local line = chn:line(0, -1)
chn:remove(0, line:len())
..
.. js:function:: Channel.get_in_len(channel)
**DEPRECATED**
This function returns the length of the input part of the buffer. When called
by a filter, this value is relative to the filter.
:param class_channel channel: The manipulated Channel.
:returns: an integer containing the amount of available bytes.
.. warning::
This function is deprecated. :js:func:`Channel.input()` must be used
instead.
.. js:function:: Channel.get_out_len(channel)
**DEPRECATED**
This function returns the length of the output part of the buffer. When called
by a filter, this value is relative to the filter.
:param class_channel channel: The manipulated Channel.
:returns: an integer containing the amount of available bytes.
.. warning::
This function is deprecated. :js:func:`Channel.output()` must be used
instead.
.. _http_class:
HTTP class
==========
.. js:class:: HTTP
This class contain all the HTTP manipulation functions.
.. js:function:: HTTP.req_get_headers(http)
Returns a table containing all the request headers.
:param class_http http: The related http object.
:returns: table of headers.
:see: :js:func:`HTTP.res_get_headers`
This is the form of the returned table:
.. code-block:: lua
HTTP:req_get_headers()['<header-name>'][<header-index>] = "<header-value>"
local hdr = HTTP:req_get_headers()
hdr["host"][0] = "www.test.com"
hdr["accept"][0] = "audio/basic q=1"
hdr["accept"][1] = "audio/*, q=0.2"
hdr["accept"][2] = "*/*, q=0.1"
..
.. js:function:: HTTP.res_get_headers(http)
Returns a table containing all the response headers.
:param class_http http: The related http object.
:returns: table of headers.
:see: :js:func:`HTTP.req_get_headers`
This is the form of the returned table:
.. code-block:: lua
HTTP:res_get_headers()['<header-name>'][<header-index>] = "<header-value>"
local hdr = HTTP:req_get_headers()
hdr["host"][0] = "www.test.com"
hdr["accept"][0] = "audio/basic q=1"
hdr["accept"][1] = "audio/*, q=0.2"
hdr["accept"][2] = "*.*, q=0.1"
..
.. js:function:: HTTP.req_add_header(http, name, value)
Appends a HTTP header field in the request whose name is
specified in "name" and whose value is defined in "value".
:param class_http http: The related http object.
:param string name: The header name.
:param string value: The header value.
:see: :js:func:`HTTP.res_add_header`
.. js:function:: HTTP.res_add_header(http, name, value)
Appends a HTTP header field in the response whose name is
specified in "name" and whose value is defined in "value".
:param class_http http: The related http object.
:param string name: The header name.
:param string value: The header value.
:see: :js:func:`HTTP.req_add_header`
.. js:function:: HTTP.req_del_header(http, name)
Removes all HTTP header fields in the request whose name is
specified in "name".
:param class_http http: The related http object.
:param string name: The header name.
:see: :js:func:`HTTP.res_del_header`
.. js:function:: HTTP.res_del_header(http, name)
Removes all HTTP header fields in the response whose name is
specified in "name".
:param class_http http: The related http object.
:param string name: The header name.
:see: :js:func:`HTTP.req_del_header`
.. js:function:: HTTP.req_set_header(http, name, value)
This variable replace all occurrence of all header "name", by only
one containing the "value".
:param class_http http: The related http object.
:param string name: The header name.
:param string value: The header value.
:see: :js:func:`HTTP.res_set_header`
This function does the same work as the following code:
.. code-block:: lua
function fcn(txn)
TXN.http:req_del_header("header")
TXN.http:req_add_header("header", "value")
end
..
.. js:function:: HTTP.res_set_header(http, name, value)
This function replaces all occurrence of all header "name", by only
one containing the "value".
:param class_http http: The related http object.
:param string name: The header name.
:param string value: The header value.
:see: :js:func:`HTTP.req_rep_header()`
.. js:function:: HTTP.req_rep_header(http, name, regex, replace)
Matches the regular expression in all occurrences of header field "name"
according to "regex", and replaces them with the "replace" argument. The
replacement value can contain back references like \1, \2, ... This
function works with the request.
:param class_http http: The related http object.
:param string name: The header name.
:param string regex: The match regular expression.
:param string replace: The replacement value.
:see: :js:func:`HTTP.res_rep_header()`
.. js:function:: HTTP.res_rep_header(http, name, regex, string)
Matches the regular expression in all occurrences of header field "name"
according to "regex", and replaces them with the "replace" argument. The
replacement value can contain back references like \1, \2, ... This
function works with the request.
:param class_http http: The related http object.
:param string name: The header name.
:param string regex: The match regular expression.
:param string replace: The replacement value.
:see: :js:func:`HTTP.req_rep_header()`
.. js:function:: HTTP.req_set_method(http, method)
Rewrites the request method with the parameter "method".
:param class_http http: The related http object.
:param string method: The new method.
.. js:function:: HTTP.req_set_path(http, path)
Rewrites the request path with the "path" parameter.
:param class_http http: The related http object.
:param string path: The new path.
.. js:function:: HTTP.req_set_query(http, query)
Rewrites the request's query string which appears after the first question
mark ("?") with the parameter "query".
:param class_http http: The related http object.
:param string query: The new query.
.. js:function:: HTTP.req_set_uri(http, uri)
Rewrites the request URI with the parameter "uri".
:param class_http http: The related http object.
:param string uri: The new uri.
.. js:function:: HTTP.res_set_status(http, status [, reason])
Rewrites the response status code with the parameter "code".
If no custom reason is provided, it will be generated from the status.
:param class_http http: The related http object.
:param integer status: The new response status code.
:param string reason: The new response reason (optional).
.. _httpclient_class:
HTTPClient class
================
.. js:class:: HTTPClient
The httpclient class allows issue of outbound HTTP requests through a simple
API without the knowledge of HAProxy internals.
.. js:function:: HTTPClient.get(httpclient, request)
.. js:function:: HTTPClient.head(httpclient, request)
.. js:function:: HTTPClient.put(httpclient, request)
.. js:function:: HTTPClient.post(httpclient, request)
.. js:function:: HTTPClient.delete(httpclient, request)
Send a HTTP request and wait for a response. GET, HEAD PUT, POST and DELETE
methods can be used.
The HTTPClient will send asynchronously the data and is able to send and
receive more than HAProxy bufsize.
The HTTPClient interface is not able to decompress responses, it is not
recommended to send an Accept-Encoding in the request so the response is
received uncompressed.
:param class httpclient: Is the manipulated HTTPClient.
:param table request: Is a table containing the parameters of the request
that will be send.
:param string request.url: Is a mandatory parameter for the request that
contains the URL.
:param string request.body: Is an optional parameter for the request that
contains the body to send.
:param table request.headers: Is an optional parameter for the request that
contains the headers to send.
:param string request.dst: Is an optional parameter for the destination in
haproxy address format.
:param integer request.timeout: Optional timeout parameter, set a
"timeout server" on the connections.
:returns: Lua table containing the response
.. code-block:: lua
local httpclient = core.httpclient()
local response = httpclient:post{url="http://127.0.0.1", body=body, dst="unix@/var/run/http.sock"}
..
.. code-block:: lua
response = {
status = 400,
reason = "Bad request",
headers = {
["content-type"] = { "text/html" },
["cache-control"] = { "no-cache", "no-store" },
},
body = "<html><body><h1>invalid request<h1></body></html>",
}
..
.. _txn_class:
TXN class
=========
.. js:class:: TXN
The txn class contain all the functions relative to the http or tcp
transaction (Note than a tcp stream is the same than a tcp transaction, but
a HTTP transaction is not the same than a tcp stream).
The usage of this class permits to retrieve data from the requests, alter it
and forward it.
All the functions provided by this class are available in the context
**sample-fetches**, **actions** and **filters**.
.. js:attribute:: TXN.c
:returns: An :ref:`converters_class`.
This attribute contains a Converters class object.
.. js:attribute:: TXN.sc
:returns: An :ref:`converters_class`.
This attribute contains a Converters class object. The functions of
this object returns always a string.
.. js:attribute:: TXN.f
:returns: An :ref:`fetches_class`.
This attribute contains a Fetches class object.
.. js:attribute:: TXN.sf
:returns: An :ref:`fetches_class`.
This attribute contains a Fetches class object. The functions of
this object returns always a string.
.. js:attribute:: TXN.req
:returns: An :ref:`channel_class`.
This attribute contains a channel class object for the request buffer.
.. js:attribute:: TXN.res
:returns: An :ref:`channel_class`.
This attribute contains a channel class object for the response buffer.
.. js:attribute:: TXN.http
:returns: An :ref:`http_class`.
This attribute contains a HTTP class object. It is available only if the
proxy has the "mode http" enabled.
.. js:attribute:: TXN.http_req
:returns: An :ref:`httpmessage_class`.
This attribute contains the request HTTPMessage class object. It is available
only if the proxy has the "mode http" enabled and only in the **filters**
context.
.. js:attribute:: TXN.http_res
:returns: An :ref:`httpmessage_class`.
This attribute contains the response HTTPMessage class object. It is available
only if the proxy has the "mode http" enabled and only in the **filters**
context.
.. js:function:: TXN.log(TXN, loglevel, msg)
This function sends a log. The log is sent, according with the HAProxy
configuration file, to the loggers relevant to the current context and/or
to stderr if it is allowed.
The exact behaviour depends on tune.lua.log.loggers and tune.lua.log.stderr.
:param class_txn txn: The class txn object containing the data.
:param integer loglevel: Is the log level associated with the message. It is
a number between 0 and 7.
:param string msg: The log content.
:see: :js:attr:`core.emerg`, :js:attr:`core.alert`, :js:attr:`core.crit`,
:js:attr:`core.err`, :js:attr:`core.warning`, :js:attr:`core.notice`,
:js:attr:`core.info`, :js:attr:`core.debug` (log level definitions)
:see: :js:func:`TXN.deflog`
:see: :js:func:`TXN.Debug`
:see: :js:func:`TXN.Info`
:see: :js:func:`TXN.Warning`
:see: :js:func:`TXN.Alert`
.. js:function:: TXN.deflog(TXN, msg)
Sends a log line with the default loglevel for the proxy associated with the
transaction.
:param class_txn txn: The class txn object containing the data.
:param string msg: The log content.
:see: :js:func:`TXN.log`
.. js:function:: TXN.Debug(txn, msg)
:param class_txn txn: The class txn object containing the data.
:param string msg: The log content.
:see: :js:func:`TXN.log`
Does the same job as:
.. code-block:: lua
function Debug(txn, msg)
TXN.log(txn, core.debug, msg)
end
..
.. js:function:: TXN.Info(txn, msg)
:param class_txn txn: The class txn object containing the data.
:param string msg: The log content.
:see: :js:func:`TXN.log`
Does the same job as:
.. code-block:: lua
function Info(txn, msg)
TXN.log(txn, core.info, msg)
end
..
.. js:function:: TXN.Warning(txn, msg)
:param class_txn txn: The class txn object containing the data.
:param string msg: The log content.
:see: :js:func:`TXN.log`
Does the same job as:
.. code-block:: lua
function Warning(txn, msg)
TXN.log(txn, core.warning, msg)
end
..
.. js:function:: TXN.Alert(txn, msg)
:param class_txn txn: The class txn object containing the data.
:param string msg: The log content.
:see: :js:func:`TXN.log`
Does the same job as:
.. code-block:: lua
function Alert(txn, msg)
TXN.log(txn, core.alert, msg)
end
..
.. js:function:: TXN.get_priv(txn)
Return Lua data stored in the current transaction (with the `TXN.set_priv()`)
function. If no data are stored, it returns a nil value.
:param class_txn txn: The class txn object containing the data.
:returns: the opaque data previously stored, or nil if nothing is
available.
.. js:function:: TXN.set_priv(txn, data)
Store any data in the current HAProxy transaction. This action replaces the
old stored data.
:param class_txn txn: The class txn object containing the data.
:param opaque data: The data which is stored in the transaction.
.. js:function:: TXN.set_var(TXN, var, value[, ifexist])
Converts a Lua type in a HAProxy type and store it in a variable <var>.
:param class_txn txn: The class txn object containing the data.
:param string var: The variable name according with the HAProxy variable
syntax.
:param type value: The value associated to the variable. The type can be
string or integer.
:param boolean ifexist: If this parameter is set to true the variable will
only be set if it was defined elsewhere (i.e. used within the configuration).
For global variables (using the "proc" scope), they will only be updated and
never created. It is highly recommended to always set this to true.
.. js:function:: TXN.unset_var(TXN, var)
Unset the variable <var>.
:param class_txn txn: The class txn object containing the data.
:param string var: The variable name according with the HAProxy variable
syntax.
.. js:function:: TXN.get_var(TXN, var)
Returns data stored in the variable <var> converter in Lua type.
:param class_txn txn: The class txn object containing the data.
:param string var: The variable name according with the HAProxy variable
syntax.
.. js:function:: TXN.reply([reply])
Return a new reply object
:param table reply: A table containing info to initialize the reply fields.
:returns: A :ref:`reply_class` object.
The table used to initialized the reply object may contain following entries :
* status : The reply status code. the code 200 is used by default.
* reason : The reply reason. The reason corresponding to the status code is
used by default.
* headers : A list of headers, indexed by header name. Empty by default. For
a given name, multiple values are possible, stored in an ordered list.
* body : The reply body, empty by default.
.. code-block:: lua
local reply = txn:reply{
status = 400,
reason = "Bad request",
headers = {
["content-type"] = { "text/html" },
["cache-control"] = {"no-cache", "no-store" }
},
body = "<html><body><h1>invalid request<h1></body></html>"
}
..
:see: :js:class:`Reply`
.. js:function:: TXN.done(txn[, reply])
This function terminates processing of the transaction and the associated
session and optionally reply to the client for HTTP sessions.
:param class_txn txn: The class txn object containing the data.
:param class_reply reply: The class reply object to return to the client.
This functions can be used when a critical error is detected or to terminate
processing after some data have been returned to the client (eg: a redirect).
To do so, a reply may be provided. This object is optional and may contain a
status code, a reason, a header list and a body. All these fields are
optional. When not provided, the default values are used. By default, with an
empty reply object, an empty HTTP 200 response is returned to the client. If
no reply object is provided, the transaction is terminated without any
reply. If a reply object is provided, it must not exceed the buffer size once
converted into the internal HTTP representation. Because for now there is no
easy way to be sure it fits, it is probably better to keep it reasonably
small.
The reply object may be fully created in lua or the class Reply may be used to
create it.
.. code-block:: lua
local reply = txn:reply()
reply:set_status(400, "Bad request")
reply:add_header("content-type", "text/html")
reply:add_header("cache-control", "no-cache")
reply:add_header("cache-control", "no-store")
reply:set_body("<html><body><h1>invalid request<h1></body></html>")
txn:done(reply)
..
.. code-block:: lua
txn:done{
status = 400,
reason = "Bad request",
headers = {
["content-type"] = { "text/html" },
["cache-control"] = { "no-cache", "no-store" },
},
body = "<html><body><h1>invalid request<h1></body></html>"
}
..
.. warning::
It does not make sense to call this function from sample-fetches. In this
case the behavior is the same than core.done(): it finishes the Lua
execution. The transaction is really aborted only from an action registered
function.
:see: :js:func:`TXN.reply`, :js:class:`Reply`
.. js:function:: TXN.set_fc_tos(txn, tos)
Is used to set the TOS or DSCP field value of packets sent to the client to
the value passed in "tos" on platforms which support this.
:param class_txn txn: The class txn object containing the data.
:param integer tos: The new TOS os DSCP.
.. js:function:: TXN.set_fc_mark(txn, mark)
Is used to set the Netfilter MARK on all packets sent to the client to the
value passed in "mark" on platforms which support it.
:param class_txn txn: The class txn object containing the data.
:param integer mark: The mark value.
.. js:function:: TXN.set_loglevel(txn, loglevel)
Is used to change the log level of the current request. The "loglevel" must
be an integer between 0 and 7 or the special value -1 to disable logging.
:param class_txn txn: The class txn object containing the data.
:param integer loglevel: The required log level. This variable can be one of
:see: :js:attr:`core.silent`, :js:attr:`core.emerg`, :js:attr:`core.alert`,
:js:attr:`core.crit`, :js:attr:`core.err`, :js:attr:`core.warning`, :js:attr:`core.notice`,
:js:attr:`core.info`, :js:attr:`core.debug` (log level definitions)
.. js:function:: TXN.set_mark(txn, mark)
Alias for :js:func:`TXN.set_fc_mark()`.
.. warning::
This function is deprecated. :js:func:`TXN.set_fc_mark()` must be used
instead.
.. js:function:: TXN.set_tos(txn, tos)
Alias for :js:func:`TXN.set_fc_tos()`.
.. warning::
This function is deprecated. :js:func:`TXN.set_fc_tos()` must be used
instead.
.. js:function:: TXN.set_priority_class(txn, prio)
This function adjusts the priority class of the transaction. The value should
be within the range -2047..2047. Values outside this range will be
truncated.
See the HAProxy configuration.txt file keyword "http-request" action
"set-priority-class" for details.
.. js:function:: TXN.set_priority_offset(txn, prio)
This function adjusts the priority offset of the transaction. The value
should be within the range -524287..524287. Values outside this range will be
truncated.
See the HAProxy configuration.txt file keyword "http-request" action
"set-priority-offset" for details.
.. _reply_class:
Reply class
============
.. js:class:: Reply
**context**: action
This class represents a HTTP response message. It provides some methods to
enrich it. Once converted into the internal HTTP representation, the response
message must not exceed the buffer size. Because for now there is no
easy way to be sure it fits, it is probably better to keep it reasonably
small.
See tune.bufsize in the configuration manual for details.
.. code-block:: lua
local reply = txn:reply({status = 400}) -- default HTTP 400 reason-phase used
reply:add_header("content-type", "text/html")
reply:add_header("cache-control", "no-cache")
reply:add_header("cache-control", "no-store")
reply:set_body("<html><body><h1>invalid request<h1></body></html>")
..
:see: :js:func:`TXN.reply`
.. js:attribute:: Reply.status
The reply status code. By default, the status code is set to 200.
:returns: integer
.. js:attribute:: Reply.reason
The reason string describing the status code.
:returns: string
.. js:attribute:: Reply.headers
A table indexing all reply headers by name. To each name is associated an
ordered list of values.
:returns: Lua table
.. code-block:: lua
{
["content-type"] = { "text/html" },
["cache-control"] = {"no-cache", "no-store" },
x_header_name = { "value1", "value2", ... }
...
}
..
.. js:attribute:: Reply.body
The reply payload.
:returns: string
.. js:function:: Reply.set_status(REPLY, status[, reason])
Set the reply status code and optionally the reason-phrase. If the reason is
not provided, the default reason corresponding to the status code is used.
:param class_reply reply: The related Reply object.
:param integer status: The reply status code.
:param string reason: The reply status reason (optional).
.. js:function:: Reply.add_header(REPLY, name, value)
Add a header to the reply object. If the header does not already exist, a new
entry is created with its name as index and a one-element list containing its
value as value. Otherwise, the header value is appended to the ordered list of
values associated to the header name.
:param class_reply reply: The related Reply object.
:param string name: The header field name.
:param string value: The header field value.
.. js:function:: Reply.del_header(REPLY, name)
Remove all occurrences of a header name from the reply object.
:param class_reply reply: The related Reply object.
:param string name: The header field name.
.. js:function:: Reply.set_body(REPLY, body)
Set the reply payload.
:param class_reply reply: The related Reply object.
:param string body: The reply payload.
.. _socket_class:
Socket class
============
.. js:class:: Socket
This class must be compatible with the Lua Socket class. Only the 'client'
functions are available. See the Lua Socket documentation:
`http://w3.impa.br/~diego/software/luasocket/tcp.html
<http://w3.impa.br/~diego/software/luasocket/tcp.html>`_
.. js:function:: Socket.close(socket)
Closes a TCP object. The internal socket used by the object is closed and the
local address to which the object was bound is made available to other
applications. No further operations (except for further calls to the close
method) are allowed on a closed Socket.
:param class_socket socket: Is the manipulated Socket.
Note: It is important to close all used sockets once they are not needed,
since, in many systems, each socket uses a file descriptor, which are limited
system resources. Garbage-collected objects are automatically closed before
destruction, though.
.. js:function:: Socket.connect(socket, address[, port])
Attempts to connect a socket object to a remote host.
In case of error, the method returns nil followed by a string describing the
error. In case of success, the method returns 1.
:param class_socket socket: Is the manipulated Socket.
:param string address: can be an IP address or a host name. See below for more
information.
:param integer port: must be an integer number in the range [1..64K].
:returns: 1 or nil.
An address field extension permits to use the connect() function to connect to
other stream than TCP. The syntax containing a simpleipv4 or ipv6 address is
the basically expected format. This format requires the port.
Other format accepted are a socket path like "/socket/path", it permits to
connect to a socket. Abstract namespaces are supported with the prefix
"abns@", and finally a file descriptor can be passed with the prefix "fd@".
The prefix "ipv4@", "ipv6@" and "unix@" are also supported. The port can be
passed int the string. The syntax "127.0.0.1:1234" is valid. In this case, the
parameter *port* must not be set.
.. js:function:: Socket.connect_ssl(socket, address, port)
Same behavior than the function socket:connect, but uses SSL.
:param class_socket socket: Is the manipulated Socket.
:returns: 1 or nil.
.. js:function:: Socket.getpeername(socket)
Returns information about the remote side of a connected client object.
Returns a string with the IP address of the peer, followed by the port number
that peer is using for the connection. In case of error, the method returns
nil.
:param class_socket socket: Is the manipulated Socket.
:returns: a string containing the server information.
.. js:function:: Socket.getsockname(socket)
Returns the local address information associated to the object.
The method returns a string with local IP address and a number with the port.
In case of error, the method returns nil.
:param class_socket socket: Is the manipulated Socket.
:returns: a string containing the client information.
.. js:function:: Socket.receive(socket, [pattern [, prefix]])
Reads data from a client object, according to the specified read pattern.
Patterns follow the Lua file I/O format, and the difference in performance
between all patterns is negligible.
:param class_socket socket: Is the manipulated Socket.
:param string|integer pattern: Describe what is required (see below).
:param string prefix: A string which will be prefix the returned data.
:returns: a string containing the required data or nil.
Pattern can be any of the following:
* **`*a`**: reads from the socket until the connection is closed. No
end-of-line translation is performed;
* **`*l`**: reads a line of text from the Socket. The line is terminated by a
LF character (ASCII 10), optionally preceded by a CR character
(ASCII 13). The CR and LF characters are not included in the
returned line. In fact, all CR characters are ignored by the
pattern. This is the default pattern.
* **number**: causes the method to read a specified number of bytes from the
Socket. Prefix is an optional string to be concatenated to the
beginning of any received data before return.
* **empty**: If the pattern is left empty, the default option is `*l`.
If successful, the method returns the received pattern. In case of error, the
method returns nil followed by an error message which can be the string
'closed' in case the connection was closed before the transmission was
completed or the string 'timeout' in case there was a timeout during the
operation. Also, after the error message, the function returns the partial
result of the transmission.
Important note: This function was changed severely. It used to support
multiple patterns (but I have never seen this feature used) and now it
doesn't anymore. Partial results used to be returned in the same way as
successful results. This last feature violated the idea that all functions
should return nil on error. Thus it was changed too.
.. js:function:: Socket.send(socket, data [, start [, end ]])
Sends data through client object.
:param class_socket socket: Is the manipulated Socket.
:param string data: The data that will be sent.
:param integer start: The start position in the buffer of the data which will
be sent.
:param integer end: The end position in the buffer of the data which will
be sent.
:returns: see below.
Data is the string to be sent. The optional arguments i and j work exactly
like the standard string.sub Lua function to allow the selection of a
substring to be sent.
If successful, the method returns the index of the last byte within [start,
end] that has been sent. Notice that, if start is 1 or absent, this is
effectively the total number of bytes sent. In case of error, the method
returns nil, followed by an error message, followed by the index of the last
byte within [start, end] that has been sent. You might want to try again from
the byte following that. The error message can be 'closed' in case the
connection was closed before the transmission was completed or the string
'timeout' in case there was a timeout during the operation.
Note: Output is not buffered. For small strings, it is always better to
concatenate them in Lua (with the '..' operator) and send the result in one
call instead of calling the method several times.
.. js:function:: Socket.setoption(socket, option [, value])
Just implemented for compatibility, this cal does nothing.
.. js:function:: Socket.settimeout(socket, value [, mode])
Changes the timeout values for the object. All I/O operations are blocking.
That is, any call to the methods send, receive, and accept will block
indefinitely, until the operation completes. The settimeout method defines a
limit on the amount of time the I/O methods can block. When a timeout time
has elapsed, the affected methods give up and fail with an error code.
The amount of time to wait is specified as the value parameter, in seconds.
The timeout modes are not implemented, the only settable timeout is the
inactivity time waiting for complete the internal buffer send or waiting for
receive data.
:param class_socket socket: Is the manipulated Socket.
:param float value: The timeout value. Use floating point to specify
milliseconds.
.. _regex_class:
Regex class
===========
.. js:class:: Regex
This class allows the usage of HAProxy regexes because classic lua doesn't
provides regexes. This class inherits the HAProxy compilation options, so the
regexes can be libc regex, pcre regex or pcre JIT regex.
The expression matching number is limited to 20 per regex. The only available
option is case sensitive.
Because regexes compilation is a heavy process, it is better to define all
your regexes in the **body context** and use it during the runtime.
.. code-block:: lua
-- Create the regex
st, regex = Regex.new("needle (..) (...)", true);
-- Check compilation errors
if st == false then
print "error: " .. regex
end
-- Match the regexes
print(regex:exec("Looking for a needle in the haystack")) -- true
print(regex:exec("Lokking for a cat in the haystack")) -- false
-- Extract words
st, list = regex:match("Looking for a needle in the haystack")
print(st) -- true
print(list[1]) -- needle in the
print(list[2]) -- in
print(list[3]) -- the
.. js:function:: Regex.new(regex, case_sensitive)
Create and compile a regex.
:param string regex: The regular expression according with the libc or pcre
standard
:param boolean case_sensitive: Match is case sensitive or not.
:returns: boolean status and :ref:`regex_class` or string containing fail
reason.
.. js:function:: Regex.exec(regex, str)
Execute the regex.
:param class_regex regex: A :ref:`regex_class` object.
:param string str: The input string will be compared with the compiled regex.
:returns: a boolean status according with the match result.
.. js:function:: Regex.match(regex, str)
Execute the regex and return matched expressions.
:param class_map map: A :ref:`regex_class` object.
:param string str: The input string will be compared with the compiled regex.
:returns: a boolean status according with the match result, and
a table containing all the string matched in order of declaration.
.. _map_class:
Map class
=========
.. js:class:: Map
This class permits to do some lookups in HAProxy maps. The declared maps can
be modified during the runtime through the HAProxy management socket.
.. code-block:: lua
default = "usa"
-- Create and load map
geo = Map.new("geo.map", Map._ip);
-- Create new fetch that returns the user country
core.register_fetches("country", function(txn)
local src;
local loc;
src = txn.f:fhdr("x-forwarded-for");
if (src == nil) then
src = txn.f:src()
if (src == nil) then
return default;
end
end
-- Perform lookup
loc = geo:lookup(src);
if (loc == nil) then
return default;
end
return loc;
end);
.. js:attribute:: Map._int
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
Note that :js:attr:`Map.int` is also available for compatibility.
.. js:attribute:: Map._ip
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
Note that :js:attr:`Map.ip` is also available for compatibility.
.. js:attribute:: Map._str
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
Note that :js:attr:`Map.str` is also available for compatibility.
.. js:attribute:: Map._beg
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
Note that :js:attr:`Map.beg` is also available for compatibility.
.. js:attribute:: Map._sub
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
Note that :js:attr:`Map.sub` is also available for compatibility.
.. js:attribute:: Map._dir
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
Note that :js:attr:`Map.dir` is also available for compatibility.
.. js:attribute:: Map._dom
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
Note that :js:attr:`Map.dom` is also available for compatibility.
.. js:attribute:: Map._end
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
.. js:attribute:: Map._reg
See the HAProxy configuration.txt file, chapter "Using ACLs and fetching
samples" and subchapter "ACL basics" to understand this pattern matching
method.
Note that :js:attr:`Map.reg` is also available for compatibility.
.. js:function:: Map.new(name, method)
Creates and load a map.
:param string name: Is the name referencing the map.
:param integer method: Is the map pattern matching method. See the attributes
of the Map class.
:returns: a class Map object.
:see: The Map attributes: :js:attr:`Map._int`, :js:attr:`Map._ip`,
:js:attr:`Map._str`, :js:attr:`Map._beg`, :js:attr:`Map._sub`,
:js:attr:`Map._dir`, :js:attr:`Map._dom`, :js:attr:`Map._end` and
:js:attr:`Map._reg`.
.. js:function:: Map.lookup(map, str)
Perform a lookup in a map.
:param class_map map: Is the class Map object.
:param string str: Is the string used as key.
:returns: a string containing the result or nil if no match.
.. js:function:: Map.slookup(map, str)
Perform a lookup in a map.
:param class_map map: Is the class Map object.
:param string str: Is the string used as key.
:returns: a string containing the result or empty string if no match.
.. _applethttp_class:
AppletHTTP class
================
.. js:class:: AppletHTTP
This class is used with applets that requires the 'http' mode. The http applet
can be registered with the *core.register_service()* function. They are used
for processing an http request like a server in back of HAProxy.
This is an hello world sample code:
.. code-block:: lua
core.register_service("hello-world", "http", function(applet)
local response = "Hello World !"
applet:set_status(200)
applet:add_header("content-length", string.len(response))
applet:add_header("content-type", "text/plain")
applet:start_response()
applet:send(response)
end)
.. js:attribute:: AppletHTTP.c
:returns: A :ref:`converters_class`
This attribute contains a Converters class object.
.. js:attribute:: AppletHTTP.sc
:returns: A :ref:`converters_class`
This attribute contains a Converters class object. The
functions of this object always return a string.
.. js:attribute:: AppletHTTP.f
:returns: A :ref:`fetches_class`
This attribute contains a Fetches class object. Note that the
applet execution place cannot access to a valid HAProxy core HTTP
transaction, so some sample fetches related to the HTTP dependent
values (hdr, path, ...) are not available.
.. js:attribute:: AppletHTTP.sf
:returns: A :ref:`fetches_class`
This attribute contains a Fetches class object. The functions of
this object always return a string. Note that the applet
execution place cannot access to a valid HAProxy core HTTP
transaction, so some sample fetches related to the HTTP dependent
values (hdr, path, ...) are not available.
.. js:attribute:: AppletHTTP.method
:returns: string
The attribute method returns a string containing the HTTP
method.
.. js:attribute:: AppletHTTP.version
:returns: string
The attribute version, returns a string containing the HTTP
request version.
.. js:attribute:: AppletHTTP.path
:returns: string
The attribute path returns a string containing the HTTP
request path.
.. js:attribute:: AppletHTTP.qs
:returns: string
The attribute qs returns a string containing the HTTP
request query string.
.. js:attribute:: AppletHTTP.length
:returns: integer
The attribute length returns an integer containing the HTTP
body length.
.. js:attribute:: AppletHTTP.headers
:returns: table
The attribute headers returns a table containing the HTTP
headers. The header names are always in lower case. As the header name can be
encountered more than once in each request, the value is indexed with 0 as
first index value. The table has this form:
.. code-block:: lua
AppletHTTP.headers['<header-name>'][<header-index>] = "<header-value>"
AppletHTTP.headers["host"][0] = "www.test.com"
AppletHTTP.headers["accept"][0] = "audio/basic q=1"
AppletHTTP.headers["accept"][1] = "audio/*, q=0.2"
AppletHTTP.headers["accept"][2] = "*/*, q=0.1"
..
.. js:function:: AppletHTTP.set_status(applet, code [, reason])
This function sets the HTTP status code for the response. The allowed code are
from 100 to 599.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:param integer code: the status code returned to the client.
:param string reason: the status reason returned to the client (optional).
.. js:function:: AppletHTTP.add_header(applet, name, value)
This function adds a header in the response. Duplicated headers are not
collapsed. The special header *content-length* is used to determinate the
response length. If it does not exist, a *transfer-encoding: chunked* is set,
and all the write from the function *AppletHTTP:send()* become a chunk.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:param string name: the header name
:param string value: the header value
.. js:function:: AppletHTTP.start_response(applet)
This function indicates to the HTTP engine that it can process and send the
response headers. After this called we cannot add headers to the response; We
cannot use the *AppletHTTP:send()* function if the
*AppletHTTP:start_response()* is not called.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
.. js:function:: AppletHTTP.getline(applet)
This function returns a string containing one line from the http body. If the
data returned doesn't contains a final '\\n' its assumed than its the last
available data before the end of stream.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:returns: a string. The string can be empty if we reach the end of the stream.
.. js:function:: AppletHTTP.receive(applet, [size])
Reads data from the HTTP body, according to the specified read *size*. If the
*size* is missing, the function tries to read all the content of the stream
until the end. If the *size* is bigger than the http body, it returns the
amount of data available.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:param integer size: the required read size.
:returns: always return a string,the string can be empty is the connection is
closed.
.. js:function:: AppletHTTP.send(applet, msg)
Send the message *msg* on the http request body.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:param string msg: the message to send.
.. js:function:: AppletHTTP.get_priv(applet)
Return Lua data stored in the current transaction. If no data are stored,
it returns a nil value.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:returns: the opaque data previously stored, or nil if nothing is
available.
:see: :js:func:`AppletHTTP.set_priv`
.. js:function:: AppletHTTP.set_priv(applet, data)
Store any data in the current HAProxy transaction. This action replaces the
old stored data.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:param opaque data: The data which is stored in the transaction.
:see: :js:func:`AppletHTTP.get_priv`
.. js:function:: AppletHTTP.set_var(applet, var, value[, ifexist])
Converts a Lua type in a HAProxy type and store it in a variable <var>.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:param string var: The variable name according with the HAProxy variable
syntax.
:param type value: The value associated to the variable. The type ca be string
or integer.
:param boolean ifexist: If this parameter is set to true the variable will
only be set if it was defined elsewhere (i.e. used within the configuration).
For global variables (using the "proc" scope), they will only be updated and
never created. It is highly recommended to always set this to true.
:see: :js:func:`AppletHTTP.unset_var`
:see: :js:func:`AppletHTTP.get_var`
.. js:function:: AppletHTTP.unset_var(applet, var)
Unset the variable <var>.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:param string var: The variable name according with the HAProxy variable
syntax.
:see: :js:func:`AppletHTTP.set_var`
:see: :js:func:`AppletHTTP.get_var`
.. js:function:: AppletHTTP.get_var(applet, var)
Returns data stored in the variable <var> converter in Lua type.
:param class_AppletHTTP applet: An :ref:`applethttp_class`
:param string var: The variable name according with the HAProxy variable
syntax.
:see: :js:func:`AppletHTTP.set_var`
:see: :js:func:`AppletHTTP.unset_var`
.. _applettcp_class:
AppletTCP class
===============
.. js:class:: AppletTCP
This class is used with applets that requires the 'tcp' mode. The tcp applet
can be registered with the *core.register_service()* function. They are used
for processing a tcp stream like a server in back of HAProxy.
.. js:attribute:: AppletTCP.c
:returns: A :ref:`converters_class`
This attribute contains a Converters class object.
.. js:attribute:: AppletTCP.sc
:returns: A :ref:`converters_class`
This attribute contains a Converters class object. The
functions of this object always return a string.
.. js:attribute:: AppletTCP.f
:returns: A :ref:`fetches_class`
This attribute contains a Fetches class object.
.. js:attribute:: AppletTCP.sf
:returns: A :ref:`fetches_class`
This attribute contains a Fetches class object.
.. js:function:: AppletTCP.getline(applet)
This function returns a string containing one line from the stream. If the
data returned doesn't contains a final '\\n' its assumed than its the last
available data before the end of stream.
:param class_AppletTCP applet: An :ref:`applettcp_class`
:returns: a string. The string can be empty if we reach the end of the stream.
.. js:function:: AppletTCP.receive(applet, [size])
Reads data from the TCP stream, according to the specified read *size*. If the
*size* is missing, the function tries to read all the content of the stream
until the end.
:param class_AppletTCP applet: An :ref:`applettcp_class`
:param integer size: the required read size.
:returns: always return a string, the string can be empty if the connection is
closed.
.. js:function:: AppletTCP.send(appletmsg)
Send the message on the stream.
:param class_AppletTCP applet: An :ref:`applettcp_class`
:param string msg: the message to send.
.. js:function:: AppletTCP.get_priv(applet)
Return Lua data stored in the current transaction. If no data are stored,
it returns a nil value.
:param class_AppletTCP applet: An :ref:`applettcp_class`
:returns: the opaque data previously stored, or nil if nothing is
available.
:see: :js:func:`AppletTCP.set_priv`
.. js:function:: AppletTCP.set_priv(applet, data)
Store any data in the current HAProxy transaction. This action replaces the
old stored data.
:param class_AppletTCP applet: An :ref:`applettcp_class`
:param opaque data: The data which is stored in the transaction.
:see: :js:func:`AppletTCP.get_priv`
.. js:function:: AppletTCP.set_var(applet, var, value[, ifexist])
Converts a Lua type in a HAProxy type and stores it in a variable <var>.
:param class_AppletTCP applet: An :ref:`applettcp_class`
:param string var: The variable name according with the HAProxy variable
syntax.
:param type value: The value associated to the variable. The type can be
string or integer.
:param boolean ifexist: If this parameter is set to true the variable will
only be set if it was defined elsewhere (i.e. used within the configuration).
For global variables (using the "proc" scope), they will only be updated and
never created. It is highly recommended to always set this to true.
:see: :js:func:`AppletTCP.unset_var`
:see: :js:func:`AppletTCP.get_var`
.. js:function:: AppletTCP.unset_var(applet, var)
Unsets the variable <var>.
:param class_AppletTCP applet: An :ref:`applettcp_class`
:param string var: The variable name according with the HAProxy variable
syntax.
:see: :js:func:`AppletTCP.unset_var`
:see: :js:func:`AppletTCP.set_var`
.. js:function:: AppletTCP.get_var(applet, var)
Returns data stored in the variable <var> converter in Lua type.
:param class_AppletTCP applet: An :ref:`applettcp_class`
:param string var: The variable name according with the HAProxy variable
syntax.
:see: :js:func:`AppletTCP.unset_var`
:see: :js:func:`AppletTCP.set_var`
.. _sticktable_class:
StickTable class
================
.. js:class:: StickTable
**context**: task, action, sample-fetch
This class can be used to access the HAProxy stick tables from Lua.
.. js:function:: StickTable.info()
Returns stick table attributes as a Lua table. See HAProxy documentation for
"stick-table" for canonical info, or check out example below.
:returns: Lua table
Assume our table has IPv4 key and gpc0 and conn_rate "columns":
.. code-block:: lua
{
expire=<int>, # Value in ms
size=<int>, # Maximum table size
used=<int>, # Actual number of entries in table
data={ # Data columns, with types as key, and periods as values
(-1 if type is not rate counter)
conn_rate=<int>,
gpc0=-1
},
length=<int>, # max string length for string table keys, key length
# otherwise
nopurge=<boolean>, # purge oldest entries when table is full
type="ip" # can be "ip", "ipv6", "integer", "string", "binary"
}
.. js:function:: StickTable.lookup(key)
Returns stick table entry for given <key>
:param string key: Stick table key (IP addresses and strings are supported)
:returns: Lua table
.. js:function:: StickTable.dump([filter])
Returns all entries in stick table. An optional filter can be used
to extract entries with specific data values. Filter is a table with valid
comparison operators as keys followed by data type name and value pairs.
Check out the HAProxy docs for "show table" for more details. For the
reference, the supported operators are:
"eq", "ne", "le", "lt", "ge", "gt"
For large tables, execution of this function can take a long time (for
HAProxy standards). That's also true when filter is used, so take care and
measure the impact.
:param table filter: Stick table filter
:returns: Stick table entries (table)
See below for example filter, which contains 4 entries (or comparisons).
(Maximum number of filter entries is 4, defined in the source code)
.. code-block:: lua
local filter = {
{"gpc0", "gt", 30}, {"gpc1", "gt", 20}}, {"conn_rate", "le", 10}
}
.. _action_class:
Action class
=============
.. js:class:: Act
**context**: action
This class contains all return codes an action may return. It is the lua
equivalent to HAProxy "ACT_RET_*" code.
.. code-block:: lua
core.register_action("deny", { "http-req" }, function (txn)
return act.DENY
end)
..
.. js:attribute:: act.CONTINUE
This attribute is an integer (0). It instructs HAProxy to continue the
current ruleset processing on the message. It is the default return code
for a lua action.
:returns: integer
.. js:attribute:: act.STOP
This attribute is an integer (1). It instructs HAProxy to stop the current
ruleset processing on the message.
.. js:attribute:: act.YIELD
This attribute is an integer (2). It instructs HAProxy to temporarily pause
the message processing. It will be resumed later on the same rule. The
corresponding lua script is re-executed for the start.
.. js:attribute:: act.ERROR
This attribute is an integer (3). It triggers an internal errors The message
processing is stopped and the transaction is terminated. For HTTP streams, an
HTTP 500 error is returned to the client.
:returns: integer
.. js:attribute:: act.DONE
This attribute is an integer (4). It instructs HAProxy to stop the message
processing.
:returns: integer
.. js:attribute:: act.DENY
This attribute is an integer (5). It denies the current message. The message
processing is stopped and the transaction is terminated. For HTTP streams, an
HTTP 403 error is returned to the client if the deny is returned during the
request analysis. During the response analysis, a HTTP 502 error is returned
and the server response is discarded.
:returns: integer
.. js:attribute:: act.ABORT
This attribute is an integer (6). It aborts the current message. The message
processing is stopped and the transaction is terminated. For HTTP streams,
HAProxy assumes a response was already sent to the client. From the Lua
actions point of view, when this code is used, the transaction is terminated
with no reply.
:returns: integer
.. js:attribute:: act.INVALID
This attribute is an integer (7). It triggers an internal errors. The message
processing is stopped and the transaction is terminated. For HTTP streams, an
HTTP 400 error is returned to the client if the error is returned during the
request analysis. During the response analysis, a HTTP 502 error is returned
and the server response is discarded.
:returns: integer
.. js:function:: act:wake_time(milliseconds)
**context**: action
Set the script pause timeout to the specified time, defined in
milliseconds.
:param integer milliseconds: the required milliseconds.
This function may be used when a lua action returns `act.YIELD`, to force its
wake-up at most after the specified number of milliseconds.
.. _filter_class:
Filter class
=============
.. js:class:: filter
**context**: filter
This class contains return codes some filter callback functions may return. It
also contains configuration flags and some helper functions. To understand how
the filter API works, see `doc/internals/api/filters.txt` documentation.
.. js:attribute:: filter.CONTINUE
This attribute is an integer (1). It may be returned by some filter callback
functions to instruct this filtering step is finished for this filter.
.. js:attribute:: filter.WAIT
This attribute is an integer (0). It may be returned by some filter callback
functions to instruct the filtering must be paused, waiting for more data or
for an external event depending on this filter.
.. js:attribute:: filter.ERROR
This attribute is an integer (-1). It may be returned by some filter callback
functions to trigger an error.
.. js:attribute:: filter.FLT_CFG_FL_HTX
This attribute is a flag corresponding to the filter flag FLT_CFG_FL_HTX. When
it is set for a filter, it means the filter is able to filter HTTP streams.
.. js:function:: filter.register_data_filter(chn)
**context**: filter
Enable the data filtering on the channel **chn** for the current filter. It
may be called at any time from any callback functions proceeding the data
analysis.
:param class_Channel chn: A :ref:`channel_class`.
.. js:function:: filter.unregister_data_filter(chn)
**context**: filter
Disable the data filtering on the channel **chn** for the current filter. It
may be called at any time from any callback functions.
:param class_Channel chn: A :ref:`channel_class`.
.. js:function:: filter.wake_time(milliseconds)
**context**: filter
Set the script pause timeout to the specified time, defined in
milliseconds.
:param integer milliseconds: the required milliseconds.
This function may be used from any lua filter callback function to force its
wake-up at most after the specified number of milliseconds. Especially, when
`filter.CONTINUE` is returned.
A filters is declared using :js:func:`core.register_filter()` function. The
provided class will be used to instantiate filters. It may define following
attributes:
* id: The filter identifier. It is a string that identifies the filter and is
optional.
* flags: The filter flags. Only :js:attr:`filter.FLT_CFG_FL_HTX` may be set
for now.
Such filter class must also define all required callback functions in the
following list. Note that :js:func:`Filter.new()` must be defined otherwise the
filter is ignored. Others are optional.
* .. js:function:: FILTER.new()
Called to instantiate a new filter. This function must be defined.
:returns: a Lua object that will be used as filter instance for the current
stream.
* .. js:function:: FILTER.start_analyze(flt, txn, chn)
Called when the analysis starts on the channel **chn**.
* .. js:function:: FILTER.end_analyze(flt, txn, chn)
Called when the analysis ends on the channel **chn**.
* .. js:function:: FILTER.http_headers(flt, txn, http_msg)
Called just before the HTTP payload analysis and after any processing on the
HTTP message **http_msg**. This callback functions is only called for HTTP
streams.
* .. js:function:: FILTER.http_payload(flt, txn, http_msg)
Called during the HTTP payload analysis on the HTTP message **http_msg**. This
callback functions is only called for HTTP streams.
* .. js:function:: FILTER.http_end(flt, txn, http_msg)
Called after the HTTP payload analysis on the HTTP message **http_msg**. This
callback functions is only called for HTTP streams.
* .. js:function:: FILTER.tcp_payload(flt, txn, chn)
Called during the TCP payload analysis on the channel **chn**.
Here is a full example:
.. code-block:: lua
Trace = {}
Trace.id = "Lua trace filter"
Trace.flags = filter.FLT_CFG_FL_HTX;
Trace.__index = Trace
function Trace:new()
local trace = {}
setmetatable(trace, Trace)
trace.req_len = 0
trace.res_len = 0
return trace
end
function Trace:start_analyze(txn, chn)
if chn:is_resp() then
print("Start response analysis")
else
print("Start request analysis")
end
filter.register_data_filter(self, chn)
end
function Trace:end_analyze(txn, chn)
if chn:is_resp() then
print("End response analysis: "..self.res_len.." bytes filtered")
else
print("End request analysis: "..self.req_len.." bytes filtered")
end
end
function Trace:http_headers(txn, http_msg)
stline = http_msg:get_stline()
if http_msg.channel:is_resp() then
print("response:")
print(stline.version.." "..stline.code.." "..stline.reason)
else
print("request:")
print(stline.method.." "..stline.uri.." "..stline.version)
end
for n, hdrs in pairs(http_msg:get_headers()) do
for i,v in pairs(hdrs) do
print(n..": "..v)
end
end
return filter.CONTINUE
end
function Trace:http_payload(txn, http_msg)
body = http_msg:body(-20000)
if http_msg.channel:is_resp() then
self.res_len = self.res_len + body:len()
else
self.req_len = self.req_len + body:len()
end
end
core.register_filter("trace", Trace, function(trace, args)
return trace
end)
..
.. _httpmessage_class:
HTTPMessage class
===================
.. js:class:: HTTPMessage
**context**: filter
This class contains all functions to manipulate a HTTP message. For now, this
class is only available from a filter context.
.. js:function:: HTTPMessage.add_header(http_msg, name, value)
Appends a HTTP header field in the HTTP message **http_msg** whose name is
specified in **name** and whose value is defined in **value**.
:param class_httpmessage http_msg: The manipulated HTTP message.
:param string name: The header name.
:param string value: The header value.
.. js:function:: HTTPMessage.append(http_msg, string)
This function copies the string **string** at the end of incoming data of the
HTTP message **http_msg**. The function returns the copied length on success
or -1 if data cannot be copied.
Same that :js:func:`HTTPMessage.insert(http_msg, string, http_msg:input())`.
:param class_httpmessage http_msg: The manipulated HTTP message.
:param string string: The data to copy at the end of incoming data.
:returns: an integer containing the amount of bytes copied or -1.
.. js:function:: HTTPMessage.body(http_msgl[, offset[, length]])
This function returns **length** bytes of incoming data from the HTTP message
**http_msg**, starting at the offset **offset**. The data are not removed from
the buffer.
By default, if no length is provided, all incoming data found, starting at the
given offset, are returned. If **length** is set to -1, the function tries to
retrieve a maximum of data. Because it is called in the filter context, it
never yield. Not providing an offset is the same as setting it to 0. A
positive offset is relative to the beginning of incoming data of the
http_message buffer while negative offset is relative to their end.
If there is no incoming data and the HTTP message can't receive more data,
a 'nil' value is returned.
:param class_httpmessage http_msg: The manipulated HTTP message.
:param integer offset: *optional* The offset in incoming data to start to get
data. 0 by default. May be negative to be relative to the end of incoming
data.
:param integer length: *optional* The expected length of data to retrieve.
All incoming data by default. May be set to -1 to get a maximum of data.
:returns: a string containing the data found or nil.
.. js:function:: HTTPMessage.eom(http_msg)
This function returns true if the end of message is reached for the HTTP
message **http_msg**.
:param class_httpmessage http_msg: The manipulated HTTP message.
:returns: an integer containing the amount of available bytes.
.. js:function:: HTTPMessage.del_header(http_msg, name)
Removes all HTTP header fields in the HTTP message **http_msg** whose name is
specified in **name**.
:param class_httpmessage http_msg: The manipulated http message.
:param string name: The header name.
.. js:function:: HTTPMessage.get_headers(http_msg)
Returns a table containing all the headers of the HTTP message **http_msg**.
:param class_httpmessage http_msg: The manipulated http message.
:returns: table of headers.
This is the form of the returned table:
.. code-block:: lua
http_msg:get_headers()['<header-name>'][<header-index>] = "<header-value>"
local hdr = http_msg:get_headers()
hdr["host"][0] = "www.test.com"
hdr["accept"][0] = "audio/basic q=1"
hdr["accept"][1] = "audio/*, q=0.2"
hdr["accept"][2] = "*.*, q=0.1"
..
.. js:function:: HTTPMessage.get_stline(http_msg)
Returns a table containing the start-line of the HTTP message **http_msg**.
:param class_httpmessage http_msg: The manipulated http message.
:returns: the start-line.
This is the form of the returned table:
.. code-block:: lua
-- for the request :
{"method" = string, "uri" = string, "version" = string}
-- for the response:
{"version" = string, "code" = string, "reason" = string}
..
.. js:function:: HTTPMessage.forward(http_msg, length)
This function forwards **length** bytes of data from the HTTP message
**http_msg**. Because it is called in the filter context, it never yields. Only
available incoming data may be forwarded, event if the requested length
exceeds the available amount of incoming data. It returns the amount of data
forwarded.
:param class_httpmessage http_msg: The manipulated HTTP message.
:param integer int: The amount of data to forward.
.. js:function:: HTTPMessage.input(http_msg)
This function returns the length of incoming data in the HTTP message
**http_msg** from the filter point of view.
:param class_httpmessage http_msg: The manipulated HTTP message.
:returns: an integer containing the amount of available bytes.
.. js:function:: HTTPMessage.insert(http_msg, string[, offset])
This function copies the string **string** at the offset **offset** in
incoming data of the HTTP message **http_msg**. The function returns the
copied length on success or -1 if data cannot be copied.
By default, if no offset is provided, the string is copied in front of
incoming data. A positive offset is relative to the beginning of incoming data
of the HTTP message while negative offset is relative to their end.
:param class_httpmessage http_msg: The manipulated HTTP message.
:param string string: The data to copy into incoming data.
:param integer offset: *optional* The offset in incoming data where to copy
data. 0 by default. May be negative to be relative to the end of incoming
data.
:returns: an integer containing the amount of bytes copied or -1.
.. js:function:: HTTPMessage.is_full(http_msg)
This function returns true if the HTTP message **http_msg** is full.
:param class_httpmessage http_msg: The manipulated HTTP message.
:returns: a boolean
.. js:function:: HTTPMessage.is_resp(http_msg)
This function returns true if the HTTP message **http_msg** is the response
one.
:param class_httpmessage http_msg: The manipulated HTTP message.
:returns: a boolean
.. js:function:: HTTPMessage.may_recv(http_msg)
This function returns true if the HTTP message **http_msg** may still receive
data.
:param class_httpmessage http_msg: The manipulated HTTP message.
:returns: a boolean
.. js:function:: HTTPMessage.output(http_msg)
This function returns the length of outgoing data of the HTTP message
**http_msg**.
:param class_httpmessage http_msg: The manipulated HTTP message.
:returns: an integer containing the amount of available bytes.
.. js:function:: HTTPMessage.prepend(http_msg, string)
This function copies the string **string** in front of incoming data of the
HTTP message **http_msg**. The function returns the copied length on success
or -1 if data cannot be copied.
Same that :js:func:`HTTPMessage.insert(http_msg, string, 0)`.
:param class_httpmessage http_msg: The manipulated HTTP message.
:param string string: The data to copy in front of incoming data.
:returns: an integer containing the amount of bytes copied or -1.
.. js:function:: HTTPMessage.remove(http_msg[, offset[, length]])
This function removes **length** bytes of incoming data of the HTTP message
**http_msg**, starting at offset **offset**. This function returns number of
bytes removed on success.
By default, if no length is provided, all incoming data, starting at the given
offset, are removed. Not providing an offset is the same that setting it
to 0. A positive offset is relative to the beginning of incoming data of the
HTTP message while negative offset is relative to the end.
:param class_httpmessage http_msg: The manipulated HTTP message.
:param integer offset: *optional* The offset in incoming data where to start
to remove data. 0 by default. May be negative to be relative to the end of
incoming data.
:param integer length: *optional* The length of data to remove. All incoming
data by default.
:returns: an integer containing the amount of bytes removed.
.. js:function:: HTTPMessage.rep_header(http_msg, name, regex, replace)
Matches the regular expression in all occurrences of header field **name**
according to regex **regex**, and replaces them with the string **replace**.
The replacement value can contain back references like \1, \2, ... This
function acts on whole header lines, regardless of the number of values they
may contain.
:param class_httpmessage http_msg: The manipulated HTTP message.
:param string name: The header name.
:param string regex: The match regular expression.
:param string replace: The replacement value.
.. js:function:: HTTPMessage.rep_value(http_msg, name, regex, replace)
Matches the regular expression on every comma-delimited value of header field
**name** according to regex **regex**, and replaces them with the string
**replace**. The replacement value can contain back references like \1, \2,
...
:param class_httpmessage http_msg: The manipulated HTTP message.
:param string name: The header name.
:param string regex: The match regular expression.
:param string replace: The replacement value.
.. js:function:: HTTPMessage.send(http_msg, string)
This function requires immediate send of the string **string**. It means the
string is copied at the beginning of incoming data of the HTTP message
**http_msg** and immediately forwarded. Because it is called in the filter
context, it never yields.
:param class_httpmessage http_msg: The manipulated HTTP message.
:param string string: The data to send.
:returns: an integer containing the amount of bytes copied or -1.
.. js:function:: HTTPMessage.set(http_msg, string[, offset[, length]])
This function replaces **length** bytes of incoming data of the HTTP message
**http_msg**, starting at offset **offset**, by the string **string**. The
function returns the copied length on success or -1 if data cannot be copied.
By default, if no length is provided, all incoming data, starting at the given
offset, are replaced. Not providing an offset is the same as setting it
to 0. A positive offset is relative to the beginning of incoming data of the
HTTP message while negative offset is relative to the end.
:param class_httpmessage http_msg: The manipulated HTTP message.
:param string string: The data to copy into incoming data.
:param integer offset: *optional* The offset in incoming data where to start
the data replacement. 0 by default. May be negative to be relative to the
end of incoming data.
:param integer length: *optional* The length of data to replace. All incoming
data by default.
:returns: an integer containing the amount of bytes copied or -1.
.. js:function:: HTTPMessage.set_eom(http_msg)
This function set the end of message for the HTTP message **http_msg**.
:param class_httpmessage http_msg: The manipulated HTTP message.
.. js:function:: HTTPMessage.set_header(http_msg, name, value)
This variable replace all occurrence of all header matching the name **name**,
by only one containing the value **value**.
:param class_httpmessage http_msg: The manipulated HTTP message.
:param string name: The header name.
:param string value: The header value.
This function does the same work as the following code:
.. code-block:: lua
http_msg:del_header("header")
http_msg:add_header("header", "value")
..
.. js:function:: HTTPMessage.set_method(http_msg, method)
Rewrites the request method with the string **method**. The HTTP message
**http_msg** must be the request.
:param class_httpmessage http_msg: The manipulated HTTP message.
:param string method: The new method.
.. js:function:: HTTPMessage.set_path(http_msg, path)
Rewrites the request path with the string **path**. The HTTP message
**http_msg** must be the request.
:param class_httpmessage http_msg: The manipulated HTTP message.
:param string method: The new method.
.. js:function:: HTTPMessage.set_query(http_msg, query)
Rewrites the request's query string which appears after the first question
mark ("?") with the string **query**. The HTTP message **http_msg** must be
the request.
:param class_httpmessage http_msg: The manipulated HTTP message.
:param string query: The new query.
.. js:function:: HTTPMessage.set_status(http_msg, status[, reason])
Rewrites the response status code with the integer **code** and optional the
reason **reason**. If no custom reason is provided, it will be generated from
the status. The HTTP message **http_msg** must be the response.
:param class_httpmessage http_msg: The manipulated HTTP message.
:param integer status: The new response status code.
:param string reason: The new response reason (optional).
.. js:function:: HTTPMessage.set_uri(http_msg, uri)
Rewrites the request URI with the string **uri**. The HTTP message
**http_msg** must be the request.
:param class_httpmessage http_msg: The manipulated HTTP message.
:param string uri: The new uri.
.. js:function:: HTTPMessage.unset_eom(http_msg)
This function remove the end of message for the HTTP message **http_msg**.
:param class_httpmessage http_msg: The manipulated HTTP message.
.. _CertCache_class:
CertCache class
================
.. js:class:: CertCache
This class allows to update an SSL certificate file in the memory of the
current HAProxy process. It will do the same as "set ssl cert" + "commit ssl
cert" over the HAProxy CLI.
.. js:function:: CertCache.set(certificate)
This function updates a certificate in memory.
:param table certificate: A table containing the fields to update.
:param string certificate.filename: The mandatory filename of the certificate
to update, it must already exist in memory.
:param string certificate.crt: A certificate in the PEM format. It can also
contain a private key.
:param string certificate.key: A private key in the PEM format.
:param string certificate.ocsp: An OCSP response in base64. (cf management.txt)
:param string certificate.issuer: The certificate of the OCSP issuer.
:param string certificate.sctl: An SCTL file.
.. code-block:: lua
CertCache.set{filename="certs/localhost9994.pem.rsa", crt=crt}
External Lua libraries
======================
A lot of useful lua libraries can be found here:
* Lua toolbox has been superseded by
`https://luarocks.org/ <https://luarocks.org/>`_
The old lua toolbox source code is still available here
`https://github.com/catwell/lua-toolbox <https://github.com/catwell/lua-toolbox>`_ (DEPRECATED)
Redis client library:
* `https://github.com/nrk/redis-lua <https://github.com/nrk/redis-lua>`_
This is an example about the usage of the Redis library within HAProxy.
Note that each call to any function of this library can throw an error if
the socket connection fails.
.. code-block:: lua
-- load the redis library
local redis = require("redis");
function do_something(txn)
-- create and connect new tcp socket
local tcp = core.tcp();
tcp:settimeout(1);
tcp:connect("127.0.0.1", 6379);
-- use the redis library with this new socket
local client = redis.connect({socket=tcp});
client:ping();
end
OpenSSL:
* `http://mkottman.github.io/luacrypto/index.html
<http://mkottman.github.io/luacrypto/index.html>`_
* `https://github.com/brunoos/luasec/wiki
<https://github.com/brunoos/luasec/wiki>`_
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